The BBC's Jacky Rowland: "Likely that the weather would have been a factor"

The dead men have been named as the pilot, Captain Philip Jarvis, 27, a single man from Colchester, and Sgt David Kinsley, 34, who was married with three children and lived in Mansfield.

One man died in the helicopter, and the other died shortly afterwards in hospital.

A third crewman, who has not been named, is in a critical condition in a military hospital near Sarajevo.

The Lynx crashed on Tuesday just outside a base in Gornji Vakuf, 40 miles west of Sarajevo, a Ministry of Defence spokesman said.

The crash happened at 4.30pm local time (3.30pm GMT) just outside the perimeter fence of the United Nations SFOR - stabilisation force - base.

The helicopter came down in Gornji Vakuf

The spokesman said there was "no suggestion" that the aircraft had been shot down but added the crash was now the subject of a military investigation.

A witness said the helicopter was flying slowly, only 500 feet off the ground, just before the crash.

"At one point the chopper made four or five spins in the air and then the noise of the engine was no longer heard," said Branko Prskalo, the owner of a grocery store in nearby Trnovaca.

He said the helicopter caught fire after hitting the ground. Air accident investigators from the UK were travelling to the scene on Wednesday morning.

Intense fire

A spokeman for SFOR said he did not know why the helicopter came down close to the base.

Speaking from Banja Luka, Bosnia Captain Michael Lyons, said it had been on a routine flight, but it was not clear if it was about to land or had just taken off.

"There was an intense fire. I'm not sure if it was an explosion," he said.

He said the rescue attempt may have been hampered by the threat of mines but he added: "I don't think there were any there at the time and there was no suggestion that any mines were involved."

The Lynx was from 669 Squadron 4 Regiment Army Air Corps which is based in the UK at Wattisham, Suffolk, the MoD said.

Since the peace force was deployed three years ago, 91 members have died while on duty in non-combat accidents. Most of them were traffic accidents or land mine blasts.

'Perfect husband and perfect father'

A relative of Sgt Kinsley said he had only been in Bosnia for about two weeks and had not wanted to go.

Sister-in-law Wendy Kinsley said he was given a week's notice informing him he would be in Bosnia for Christmas and away from his wife Angie and three daughters Christina, 13, Stacey, seven, and Kerry-Anne, three.

She said Sgt Kinsley, who had been in the army for about 12 years and moved to Woodbridge, near Ipswich, Suffolk, had served in Northern Ireland and married just before going to the 1991 Gulf War.

Mrs Kinsley said: "Unusually, this time he didn't want to go. We were going to have a surprise party for him when he came back."

She said he was considering leaving the army after serving six months in Bosnia.