Eight British servicemen who were held in Iran for three days are now back with UK forces in Iraq, defence chiefs have confirmed.
The servicemen have returned to British units in Iraq
Their release on Thursday followed a three-day diplomatic stand-off between London and Tehran after they were seized in the Shatt al-Arab waterway.
The six Royal Marines and two Royal Navy sailors are "fit, well and in good heart", Iraq's UK chief of staff said.
Colonel James Bashall said he hoped they would return to their duties soon.
The eight servicemen flew out of Iran in the early hours of Friday, stopping briefly in Kuwait.
The UK's Ministry of Defence said the detainees had been part of a Royal Navy training team heading to Basra when they were detained by Iranian guards.
They had been helping to re-train the Iraqi river patrol on a waterway renowned for its use by smugglers and foreign militants trying to infiltrate Iraq.
The southern stretch of the Shatt al-Arab forms the border between Iran and Iraq.
Iran said the vessels had entered its waters without prior permission.
Iranian protestors demanded a trial and conviction for the servicemen
The BBC's Jim Muir in Tehran said the release of the men came after a final round of delicate negotiations, including eight hours of talks between British officials and representatives of Iran's Revolutionary Guard.
He said their departure was greeted by "an almost audible sigh of relief from the embassy".
Officials had feared the men's presence in Tehran might lead to further hostile demonstrations against British policy and presence in Iraq.
Windows at the embassy have been smashed and there have been a series of demonstrations by hardliners in recent weeks.
And there were also small demonstrations in Tehran on Thursday where Iranian protestors held placards demanding a trial and conviction for the servicemen.
The two countries are in disagreement over human rights issues and Iran's nuclear involvements.
But Britain has kept up a policy of constructive engagement with Iran which may have contributed to the prompt release of the servicemen at such a sensitive time.
UK Foreign Secretary Jack Straw welcomed the troops' release on Thursday.
"I'm obviously very pleased indeed, as, I know, their families and service colleagues will be, that they are now in British care," he said.
THE SHATT AL-ARAB
120 miles of tidal waterway
Formed by Tigris and Euphrates rivers
Subject to 1639 Persian-Ottoman treaty
Southern stretch forms border between Iraq and Iran
River is vital trade route for both countries
Control of river one of disputes causing Iran-Iraq war in 1980
Mr Straw defended the fact that it has taken four days to secure the release of the men.
"These things do sometimes take time," he said.
Downing Street also welcomed the men's release.
"We are glad that the matter has been able to be resolved diplomatically," said Prime Minister Tony Blair's official spokesman.
The servicemen are thought to come from two Scotland-based units - Arbroath-based 45 Commando and the Fleet Standby Rifle Troop from Faslane on the Clyde - and from the 539 Assault Squadron in Plymouth, south-west England.
The father of one of the men said he was "absolutely delighted" they had been released.
"It's the news we've been waiting for," said Graham Reid, whose 24-year-old son David was among those detained.
"There were some dark moments over the last few days, especially when we saw them on TV blindfolded, but this is brilliant."