Last updated at 19:38pm on 29th March 2007
Iran has released a second letter from kidnapped British marine Faye Turney in which she calls on Tony Blair to withdraw British troops from Iraq.
The letter was released by the Iranian embassy in London, which stated that Turney was the author.
"Isn't it time for us to start withdrawing our forces from Iraq and let them determine their own future?" said the letter, addressed to the British parliament.
The second letter allegedly written by Faye Turney
Some language experts are already questioning the letter's validity, the suggestion being that the language used indicates the letter is an English translation of a Farsi original.
Turney's release is on hold after Iran accused Britain of having an "incorrect attitude".
The move comes on the day when Iranian television released footage of the operation to seize the 15 British naval personnel last week and presented what it claimed was evidence of the Britons encroaching into Iranian territory.
But Britain said the sailors and marines were detained in Iraqi waters and said global positioning data proved its position.
Faye Turney and the other British marines held captive as they appeared on state Iranian TV. Faye, who describes her captors as 'compassionate' has apologised for entering Iran's waters
The announcement that Turney's release is on hold by the head of Iran's supreme national security council Ali Larijani reperesented a clear u-turn and dashed hopes that the 26-year-old mother would be released "very soon".
New TV footage shows Iranians en route to seizing 15 British sailors last week
But Mr Larijani said on state television today: "It was announced that a woman in the group would be freed, but (this development) was met with an incorrect attitude. Naturally, (the release) will be suspended and it will not take place."
The hostage crisis also took a sinister new turn today as a hate mob in Tehran demanded that the 15 captured British Navy personnel be hanged.
Protesters waved placards demanding "15 British aggressors must be executed" outside the foreign ministry.
Earlier today the head of the United Nations personally intervened in the British hostage crisis.
The dramatic move by Secretary-General Ban Ki-moon came as the tense international stand-off entered its sixth day.
Mr Ban held talks with Iranian foreign minister Manouchehr Mottaki in an attempt to negotiate the release of the 15 Navy personnel. Confirmation of the meeting emerged from the Saudi capital Riyadh shortly after Foreign Secretary Margaret Beckett urged Mr Ban to get involved.
Britain will begin moves to push for a UN Security Council resolution that will "deplore" the detention of the seven Royal Marines and eight sailors including Leading Seaman-Faye Turney who was paraded on Iranian TV wearing a headscarf. Iran had earlier upped the stakes by telling Britain: "Apologise before they go free."
The demand by Mr Mottaki was described by one senior British diplomat as "impossible to meet". The Foreign Office rejected Iran's call for an apology, insisting Britain would "hold its ground" until the captives are released.
The sabre-rattling by Tehran reversed Iran's claim yesterday that 26-year-old Leading Seaman Turney would be set free.
Mr Mottaki said: "This can be solved but they have to show that it was a mistake. That will help us to end this issue."
His intervention raises fears that the crisis could last for weeks or months. In 1979 Iran held 60 American diplomats captive for 444 days and experts today warned Britain faced a similar situation.
Mr Mottaki offered to allow British diplomats to visit the hostages who are thought to be in Tehran.
Government officials produced data it said proved the boarding party from HMS Cornwall was two miles inside Iraqi waters when the group was seized on Friday.
Tony Blair vowed to "ratchet up" the pressure on Iran. He called for an "uncoditional release" of the hostages.
He said: "The important thing is we just keep making it very, very clear to the Iranian government it is not a situation that will be relieved by anything but the unconditional release of all our people."
It is understood that Mrs Beckett has been lobbying Iran's neighbouring states - including Iraq, Saudi Arabia and Oman - to press Iranian president Mahmoud Ahmadinejad to release the Britons.
She will ask EU leaders for support at a summit this weekend.
In an interview broadcast on Iranian TV, Leading Seaman Turney said the group had been seized in the Gulf because they had "obviously trespassed" in Iranian waters. She said her captors had been friendly and that everyone was unharmed.
"Obviously we trespassed into their waters," she said at one point, her voice audible under a simultaneous-Arabic translation. "They were very friendly and very hospitable, very thoughtful, nice people." The broadcast included footage of other marines and sailors sitting in the same room eating a meal.
It also showed a letter from Leading Seaman Turney to her parents in which she said the Navy personnel had "apparently" crossed into Iranian waters, and asked the couple to look after her three-year-old daughter Molly and her husband Adam. The Foreign Office reacted furiously to the broadcast, calling the screening "completely unacceptable".
One of the marines was named today as 26- year-old Danny Masterton, from Muirkirk, Ayrshire. His father, a retired professional footballer, said: "We just want Danny home."
Faye's letter telling her family not to 'worry' about her and that she is 'staying strong'
Video footage on state TV of Tehran parading its captives inflamed the worsening crisis - and led to demands for decisive action from the Foreign Office.
Faye Turney, the mother of a girl aged three, was singled out by the cameras in the first glimpse of the hostages since they were seized by Iran's Revolutionary Guards six days ago. Tehran had earlier claimed it was ready to release the sea survival expert 'very soon', but she showed clear signs of strain.
Words she was forced to write and speak for Tehran TV, apparently confessing that the Britons had 'trespassed' into Iranian waters, spoke of being well treated by her 'compassionate' captors.
But the harrowing footage of Mrs Turney, whose husband Adam and daughter Molly wait anxiously at their family home in Plymouth, told a different story.
Gone was the fresh-faced, enthusiastic young sailor filmed by the BBC on HMS Cornwall only hours before the British forces were captured at the mouth of the Shatt-al-Arab waterway.
She was evidently traumatised - at one point seen nervously sucking on a cigarette - in footage which the Foreign Office described as 'completely unacceptable' and British diplomats said was a clear breach of the Geneva Convention.
In the broadcast Mrs Turney, filmed in front of brightly-coloured curtains, is heard saying: "My name is Leading Seaman Faye Turney. I come from England. I serve on Foxtrot Nine Nine. I have been in the Navy nine years. I live in England.
"I was arrested on Friday March 23. Obviously we trespassed into their waters.
"They were very friendly and very hospitable, very thoughtful, good people.
"They explained to us why we had been arrested. There was no aggression, no hurt, no harm. They were very, very compassionate.'
A letter allegedly handwritten by Mrs Turney and addressed to "Dear Mum and Dad", says: "We were out in the boats when we were arrested by Iranian forces as we had apparently gone into Iranian waters. I wish we hadn't because then I would be home with you all right now."
She continues: "I have written a letter to the Iranian people to apologise for us entering into their waters. Please don't worry about me. I'm staying strong. Hopefully it won't be long till I'm home to get ready for Molly's birthday party and with a present from the Iranian people."
She ends: "Look after everyone for me, especially Adam and Molly, I love you all more than you will ever know."
Leading Seaman Faye Turney, who was one of the sailors captured, is being kept separately from the other hostages
Not all the 15 captured sailors and Marines were shown during the brief broadcast. Only two other captives have been publicly identified, Marines Danny Masterton, 22, from Muirkirk, Ayrshire, and Paul Barton, 21, from Southport.
Condemnation of the broadcast was immediate. Defence Secretary Des Browne said: "It is totally unacceptable to parade our people in this way."
Tory former Foreign Secretary Sir Malcolm Rifkind said the pictures were "totally repugnant". He said: "This is a PR exercise. If they believed in their own propaganda, they would release all of our personnel.
"We need to make clear there will be no concessions and they will suffer harsher penalties unless our personnel are handed over.'
War zone: British marines patrolling aboard an inflatable off Basra
Mrs Turney's husband declined to respond to the Iranian pictures but a friend, Kim Slater, 49, said: 'It is a very shocking film. She looked very uncomfortable with what she was saying. There is something not right in her eyes. I am sure she has been forced to do that and say those things.'
The dangerous game of brinkmanship at a time of world tension over Iran's nuclear programme moved to a new level when Ministry of Defence officials told how the Iranians had launched an 'unprovoked, unprecedented and improper' attack last Friday.
They published detailed evidence of how heavily-armed Iranian gunships had 'ambushed' the British personnel while they were patrolling in Iraqi waters.
Defence chiefs also released satellite pictures and graphics which prove the British boats were well within Iraq waters - despite Iranian claims that they had strayed into their territory.
The data shows that the Navy personnel were 1.7 nautical miles inside the Iraqi part of the Shatt al Arab waterway, which forms a boundary between the countries.
The Ministry of Defence said it "unambiguously contested" claims from Tehran that the UK vessel was in their waters.
Deputy chief of the defence staff Vice Admiral Charles Style said their detention at gunpoint was "unjustified and wrong".
He said the British personnel had carried out an "entirely routine" boarding of an Indian dhow carrying a suspicious cargo of cars off the coast of Iraq.
The ship's co-ordinates had been confirmed by the Iraqi foreign minister and verified by the Indian vessel's captain. They confirmed the ship was inside Iraqi waters.
The Vice Admiral also disclosed that the Iranians had changed their account of where the incident had taken place after it was pointed out that the first set of co-ordinates they gave were in Iraqi waters.
The Prime Minister, who spoke to George Bush yesterday about the growing crisis, told MPs: "It is now time to ratchet up the diplomatic and international pressure in order to make sure the Iranian government understands their total isolation on this issue."
He also defended the boarding party's 'entirely sensible' decision not to fight back against their captors, as they were heavily outnumbered and it would have led to "severe loss of life".
However the decision is being angrily criticised around the world, particularly in the U.S., with talk of "timidity" and "impotence" in the face of Iran's aggression.
One irate critic declared Britain had "covered itself with shame" for failing to show a more aggressive response to Iran.
In a New York newspaper article, military historian Arthur Herman claimed: "The escorting ship HMS Cornwall could have blown the Iranian naval vessel out of the water."
One reader wrote: "The United Kingdom is acting like the French. Say what you want about President Bush, but I bet the Iranian madmen are not mad enough to try this on our Navy."