Iran has broadcast a film of the lone woman among 15 Royal Navy personnel seized in the Gulf last week, in which she says she "obviously trespassed" into Iranian territory.

As the seven sailors and eight Marines were paraded on Iranian state television, Leading Seaman Faye Turney was shown separately, wearing a headscarf and smoking a cigarette.

An apparent recording of the 26-year-old said: "I am 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.”

The broadcast was accompanied by what was claimed to be a letter from Ms Turney to her parents, which was released by the Iranian Embassy in London. In the letter, Ms Turney said they had "apparently" gone into Iranian waters and repeated her assurances that was being treated well by her captors.

"We were out in the boats when we were arrested by Iranian forces as we had apparently gone into Iranian waters," the letter said. "I wish we hadn’t because then I’d be home with you all right now."

The footage, condemned immediately by the Foreign and Commonwealth Office as "completely unacceptable", was made available at the end of a day of increasingly tense diplomatic gestures. This morning the Ministry of Defence published satellite coordinates which commanders said proved that the personnel were 1.7 nautical miles inside Iraqi waters when they were "ambushed" by the Iranian Revolutionary Guard.

The Foreign Secretary, Margaret Beckett, then told MPs that Britain was immediately freezing all bilateral ties with Iran — except for negotiations directly concerning the 15. "They should not be under any doubt at all about how seriously we regard this act, which is unjustified and wrong," Mrs Beckett said.

Iran responded by stating that the "first stage" of the investigation into the capture was nearly complete and hinted that Leading Seaman Turney could be released as early as this evening. "Today or tomorrow, the lady will be released," Manouchehr Mottaki, the Foreign Minister, said on the sidelines of an Arab summit in Riyadh.

The sixth day of the hostage crisis began with a briefing by Vice-Admiral Style, Deputy Chief of the Defence Staff, who displayed nautical charts and photographs showing the position of the group when they were seized.

Vice-Admiral Style said that their coordinates had been confirmed by the skipper of an Indian-registered merchant vessel that the sailors had just inspected when they were captured.

The Navy chief said that the group were engaged in routine anti-smuggling patrols under a UN Security Council mandate at the time, operating with the authorisation of Baghdad.

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