Britain has said it is very concerned UK Navy personnel captured by Iran may have been coerced, as footage showed one of them apologising for entering Iranian waters.
In a statement, British Foreign Secretary Margaret Beckett said: 'I am very concerned about these pictures and any indication of pressure on or coercion of our personnel'.
She added that they were carrying out a routine operation 'in accordance with international law and under a United Nations resolution in support of the Iraqi government'.
Eight British sailors and seven marines were detained by Iranian Revolutionary Guards on Friday, triggering a diplomatic crisis with Britain.
Iranian television showed footage today of several of the British sailors and also released the text of a letter that it said the only woman in the group, Faye Turney, had written.
Ms Turney apologised in the letter for trespassing in Iranian waters and said the group was being well cared for.
The British Foreign Secretary said she was particularly disappointed that a private letter had been used in a way which can only add to the distress of the families.
Earlier, reports from Iran said Tehran would free 26-year-old Faye Turney.
However, a British diplomat in Tehran said the embassy had not heard anything officially about this from the Iranian side.
British Prime Minister Tony Blair has condemned the seizure of the sailors and marines saying it was unacceptable, wrong and illegal.
Officials have presented maps which they claim proves that the sailors and marines were 2.7km within Iraqi waters when they were seized.
Britain has insisted that the eight sailors and seven marines were conducting 'routine' anti-smuggling operations when they were seized at gunpoint in the Shatt al-Arab waterway in the north of the Persian Gulf on Friday.
Tehran says they had intruded into Iranian waters, though that claim is contested by Iraq.
