Ministry of Defence sources said that after being debriefed following their release from detention, the men had said that because they were “significantly outgunned” they decided to go peacefully with their Iranian captors.

The new twist to the confrontation between Iran and Britain ten days ago was revealed in a written Commons answer by Mr Hoon. He said the British military personnel had insisted they were operating in Iraqi territorial waters in the Shatt al-Arab waterway in three patrol boats but were then “forcibly escorted” into the Iranian side and taken to a port in southern Iran.

Before they were released, two of the eight men appeared on an Iranian satellite television channel and apologised for having mistakenly entered Iranian territorial waters. All eight men were paraded on television with blindfolds on.

Mr Hoon said the men’s version of events would be helped by the recovery of navigational information in the global positioning system equipment carried by the crews. However, so far the Iranian Revolutionary Guard has refused to return either the equipment or the boats and weapons.

Mr Hoon said the Government was “very concerned” about the blindfolding of the men and had made representations to Tehran.

As British diplomats continue to negotiate for the return of the two Boston Whalers and one army combat support vessel, three of the eight military personnel have now returned to Britain, one of them for medical treatment.

The other two men have returned because their tour of duty in Iraq has been completed. They were part of a team training the Iraqi river police and coastal defence services.

Although Tehran has agreed “in principle” to return the boats, no agreement has been reached about the manner in which they can be given back.

The options include sending another team of British personnel to pick them up, or allowing the Revolutionary Guard to steer them to the middle of the Shatt al-Arab waterway for handover. But there had been little progress, diplomatic sources said.

There was a confrontation in July last year when the Revolutionary Border Guards moved several border observation posts about three-quarters of a mile inside Iraq, into the marshland north and east of Basra. This provoked intensive negotiations before the Iranians agreed to move the posts back into their territory.

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