A British man has described how he, his wife and an Australian man were held for 13 days by Iranian authorities during a sailing trip.
Rupert and Linda Wise and Paul Shulton were seized by the Iranian Navy as they sailed from their home in Dubai to a disputed island in the Gulf.
Mr Wise said they still do not know why they were questioned for days while kept under armed guard.
They were freed after intense pressure from the British Foreign Office.
The Iranian embassy in London was not available to comment.
Foreign Secretary Jack Straw said "a good deal of work behind the scenes" had helped secure their release.
"It has been distressing for the Wises and for their family," he said.
"I am very glad that they have been released safely and without any charge by the Iranians."
The trio were seized at gun point by Iranian Navy patrol boats on 28 October, when they sailed their boat to the disputed island of Abu Musa, which is claimed by both Iran and the United Arab Emirates.
They were then taken to the Iranian port of Bandar Abbas, where they were questioned repeatedly by officials.
Linda Wise said they had "blundered" into an international situation involving the island, whose ownership is disputed by Iran and the United Arab Emirates, and the officials eventually realised the trio were "innocent".
After days of being denied consular access and not even told why they were being held, they were eventually allowed to make a phone call home to their children in Dubai.
Linda Wise said the couple had "blundered" by going to the island
"[We had contact] with our family, but repeatedly denied access to the Foreign Office and indeed we were forbidden to say where we were," Mr Wise told BBC Radio 4's Today programme.
"We were kept under lock and key, not allowed out, armed guards outside, guards inside, for the full period of our detention.
"We were hostages."
The Foreign Office was then alerted, allowing the British Embassy in Tehran to negotiate their hand-over to British officials.
But as they were about to board a flight home last Monday, the trio were re-arrested at the airport by the Iranian judiciary and taken to a secret location in Tehran, breaking a carefully negotiated agreement between the two countries' foreign offices.
Mr Wise described being "carted straight into a mini-van with curtains round the windows. We went out at very, very fast driving speed.
"About four minutes out we screamed to a halt, changed vehicles - presumably to throw off the British Ambassador and team who were in the airport building waiting for us."
They were then taken to a five-star Tehran hotel, but given no information about what was happening.
"The guys looking after us were always very courteous, but always referred to higher authority and looked completely clueless when we asked what was going on."
Mr Wise told the BBC they were not physically abused but had gone through what he called "mental torture".
Mr and Mrs Wise, who is originally from Glasgow, finally flew back to their home in Dubai early Friday morning.