A body thought to be of one of the five British hostages captured in Baghdad in 2007 was passed to the embassy in Iraq yesterday.

The identity has yet to be confirmed but it is believed to be either Alan McMenemy or Alec MacLachlan, who were kidnapped while working as bodyguards.

Six weeks ago the families of the two men were informed by the Government that, following reports from Iraq, it was considered “very likely” they were dead.

The man they were guarding, computer specialist Peter Moore, is still thought to be alive but the bodies of two other security guards, Jason Swindlehurst and Jason Creswell, were recovered earlier this year.

The five men were taken hostage by a heavily armed group of about 40 men dressed as security forces while inside the Iraqi ministry of finance.

Gordon Brown said he was “deeply saddened” after being told that a body had been handed to the British embassy in Baghdad. A Downing Street spokesman said: “A further body, which the Iraqi authorities believe to be one of the British hostages taken in 2007, has been passed to the British embassy in Baghdad. A process is now under way to urgently establish identity.

“The Prime Minister is in close touch with the Iraqi Prime Minister about this case.

“He will leave no stone unturned in the Government's efforts to secure the release of the remaining hostages. The Prime Minister's thoughts are with their families at this extremely difficult time.”

Foreign Secretary David Miliband said the hunt to track down the men responsible for the kidnapping of the five Britons continued. “Our cross-government effort by teams in London and Baghdad continues unabated,” he said last night. “This distressing news will not diminish our determination.

“Hostage-taking is never justified. Britain's long-standing policy is well-known: we talk to anyone who might be able to help but we do not make substantive concessions to hostage-takers. This is not an easy policy — sometimes it is agonising — but it is right.”

It was not yet possible, he said, to “definitively confirm” either that the body was that of a hostage or which one it was.