Iranian state television on Thursday broadcast a few seconds of video that it says was of the seizure last week of 15 British sailors and marines, with the sound of gunfire and a helicopter visible overhead.
The five-second video showed inflatable boats on choppy seas. Gunshots could be heard and a helicopter was visible hovering above the vessels. The Royal Navy crew members then appeared seated in an Iranian guard boat, presumably after their capture.
Shortly after Iran aired the video, Britain's Sky News said Iran had released another letter by captured sailor Faye Turney calling for the withdrawal of troops from Iraq.
The letter, which was read on the program, asked British lawmakers: "Isn't it time to start withdrawing our forces from Iraq and let them determine their own future?" It was not possible to verify the authenticity of the letter.
Meanwhile, Britain took its case to the United Nations Thursday, asking the Security Council to support a statement that would "deplore" Tehran's action and demand their immediate release.
Late Thursday, the U.N. Security Council expressed "grave concern" at the capture of the British sailors and called for an early resolution of the problem.
Iran's chief nuclear negotiator Ali Larijani said Iran may delay the release of Turney, the one female British sailor, if Britain takes the issue to the U.N. Security Council or freezes relations.
Speaking on Iranian state radio, Larijani said: "British leaders have miscalculated this issue."
If Britain follows through with its policies on the 15 British sailors and marines detained by Iran last week, Larijani said "this case may face a legal path," a clear reference to Iran's prosecuting the sailors in court.
Britain rejected a demand Thursday by Iran's foreign minister that it admit its 15 sailors and marines entered Iranian waters. Tehran said such an admission could resolve the standoff over their capture.
Since the crew's detention, Britain has insisted they were in Iraqi waters. A Foreign Office official in London said no admission would be forthcoming because "the detention is completely wrong, illegal and unacceptable and we've set out the reasons why."
The official, who spoke on condition of anonymity in line with department policy, pointed to the satellite positioning coordinates released by the Defense Ministry on Wednesday that the military said showed the crew was seized 1.7 nautical miles inside Iraqi waters.
U.N. chief Ban Ki-moon, meanwhile, held talks Thursday with Iran's foreign minister in the Saudi capital, Riyadh, in the world body's first direct diplomatic foray into the British-Iranian dispute.
Ban's spokeswoman, Soung-Ah Choi, said the U.N. secretary-general was addressing a number of issues in the talks and that the detention of the Britons was among them. She would not give immediate details on the talks, which were still ongoing.
Ban and Iranian Foreign Minister Manouchehr Mottaki were both attending a summit of Arab leaders in the Saudi capital, Riyadh.
Tensions over the detention escalated Wednesday as Iranian television showed video of the detained Britons that showed Turney saying her group had "trespassed" in Iranian waters. Britain angrily denounced the video as unacceptable and froze most dealings with the Mideast nation.
Tehran did say early Thursday that British officials would be allowed to meet with the detainees — a demand Britain has been making since the troops' capture.
The British Broadcasting Corporation reported, however, that officials in the Foreign Office in London, and on the ground at the British embassy in Tehran, had not been successful in getting Iran to follow through with that agreement.
"With Iran's foreign minister now saying that Tehran will allow British officials to meet with the detained British sailors and marines, the crisis is turning to at least some level of diplomacy," said CBS News foreign affairs analyst Pamela Falk. "But the longer the soldiers remain in Iranian custody, the more volatile the crisis becomes, particularly with increased U.S. and British military hardware in the Gulf."
Mottaki said that Iran will look into releasing Turney "as soon as possible."
He said that if the alleged entry into Iranian waters was a mistake "this can be solved. But they have to show that it was a mistake. That will help us to end this issue."
"Admitting the mistake will facilitate a solution to the problem," he said. Mottaki said Iran had GPS devices from the seized British boats that showed they were in Iranian territory.
A brief video of the captured Britons was shown Wednesday on Iran's Arabic language satellite television station, Al-Alam.
One segment showed sailors and marines sitting in an Iranian boat in open waters immediately after their capture.
The video also displayed what appeared to be a handwritten letter from Turney, 26, to her family.
"I have written a letter to the Iranian people to apologize for us entering their waters," it said. The letter also asks Turney's parents in Britain to look after her 3-year-old daughter, Molly, and her husband, Adam.
The video showed Turney in checkered head scarf and her uniform eating with other sailors and marines. Later, wearing a white tunic and black head scarf, she sat in a room before floral curtains and smoked a cigarette.
Turney was the only detainee to be shown speaking, giving her name and saying she had been in the navy for nine years.
"Obviously we trespassed into their waters," Turney said at one point. "They were very friendly and very hospitable, very thoughtful, nice people. They explained to us why we've been arrested. There was no harm, no aggression."
Prime Minister Tony Blair's office on Thursday condemned the decision to parade the captured British sailors and marines on television.
"Nobody should be put in that position. It is an impossible position to be put in," said Blair's spokesman, who spoke on condition of anonymity in keeping with government policy. "It is wrong. It is wrong in terms of the usual conventions that cover this. It is wrong in terms of basic humanity."
The third Geneva Convention bans subjecting prisoners of war to intimidation, insults or "public curiosity." Because there is no armed conflict between Iran and Britain, the captives would not technically be classified as prisoners of war.
Beckett said Britain would focus all its efforts on resolving the issue.
Blair's government announced it was freezing all dealings with Iran except to negotiate the release of its personnel, adding to a public exchange of sharp comments that helped fuel a spike in world oil prices.
President Bush discussed the 15 Britons with Blair during a secured video conference call Wednesday, White House deputy press secretary Dana Perino said. "The president fully backs Tony Blair and our allies in Britain," she said.
British officials have said the 15 Britons were taken captive after completing a search of a civilian ship near the mouth of the Shatt al-Arab waterway, which forms the border between Iran and Iraq.