The Royal Navy's head has defended the actions of 15 British personnel seized by Iran and UK operations in the Gulf.
First Sea Lord Admiral Sir Jonathon Band said the crew "reacted extremely well in very difficult circumstances".
Admiral Band also said British boarding operations being carried out in the Gulf had been "absolutely proper", but there would be a "complete review".
He was reacting to criticism that the crew, freed on Thursday after being held for 13 days, gave up too easily.
The captured personnel appeared on Iranian television admitting they had strayed into Iran's territorial waters, a claim the UK denies.
Lt Gen Sir Michael Gray, former commander of the 1st Battalion of the Paras, was quoted in the Daily Mail as describing the situation as a "shambles".
And Amyas Godfrey, an associate fellow of the Royal United Services Institute (RUSI), previously said the personnel could have stood up to their captors more.
Some of the 15 personnel will speak at a press conference later.
Admiral Band told BBC Radio 4's Today programme: "This incident was a most extraordinary act conducted in those waters...
"I think they acted with considerable dignity and a lot of courage.
"They appear to have played it by the rules, they don't appear to have put themselves into danger, others into danger, they don't appear to have given anything away".
The navy has, however, begun a review of the circumstances leading to the capture.
Admiral Band said: "Clearly, whenever things go wrong - and certainly this is not an incident we at all wanted - we will review everything that we normally do.
"Was the intelligence correct? We will look at the equipment, we will look at the procedures, we will look at all the things that happened. We certainly wouldn't want this to happen again."
Admiral Band said the review would also examine the rules of engagement for UK forces operating in the area.
However, he said the decision to board and search the merchant ship that led to the seizure of the navy personnel had been "absolutely proper".
The crew were stationed aboard HMS Cornwall
"We operate in a coalition, under operating procedures which are set to the conditions at the time of the event.
"As far as I'm aware they were conducted entirely correctly, the procedures were correct for the situation on the ground as the commander saw it."
He said UK boarding operations had stopped for now, but coalition operations were continuing under British command.
He added the Iranians were not considered to be "the enemy", and there was no question of them having been spied on.
Earlier, an MoD spokesman said the UK would continue to ask Iran to return its two captured boats used by the 15 sailors and marines, but he held out little hope of success.
The freed personnel were flown to the Royal Marine base at Chivenor, in north Devon, on Thursday, after arriving at Heathrow.
CAPTURED NAVY PERSONNEL
Chris Air, 25, from Altrincham in Cheshire
Mark Banks, 24, of Lowestoft, Suffolk
Paul Barton, of Southport, Merseyside
Arthur Batchelor, 20, of Plymouth
Felix Carman, 26, of Swansea
Christopher Coe, 31, of Huddersfield
Dean Harris, 24, of Carmarthen, west Wales
Danny Masterton, 26, of Muirkirk, Ayrshire
Adam Sperry, 22, of Wigston, near Leicester
Nathan Summers, of Hayle, Cornwall
Joe Tindell, 21, of south London
Faye Turney, 26, originally from Shropshire
Several said they had been well-treated in Iran, but there have been suggestions some may have been held in solitary confinement.
Lt Col Andy Price, who met the group at the airport, said there had been "times when they were left alone", but refused to elaborate.
The MoD said the freed personnel had roast chicken and roast beef before enjoying drinks with their loved ones on Thursday.
In a press conference outside Downing Street, Tony Blair welcomed the crew's safe return.
He said "no deal" had been done with the Iranians to secure their release, despite claims by Iran it received a written apology from Britain on Tuesday.
And he contrasted the return unharmed of the Britons with four soldiers killed in Basra in Iraq on the same day.