Insurgents claimed to have shot down a British military plane north of Baghdad over the weekend, and Al-Jazeera television aired a videotape from guerrillas Monday showing flaming wreckage of a plane. Britain said all 10 personnel on the flight were missing and presumed dead.

The authenticity of the videotape could not be confirmed. It showed a finger pressing a button, and then images of two missiles or rockets flying up into the air. The video did not show any impact with a plane. Instead, it cut to footage of people walking through a plane's wreckage burning on the ground.

In London, officials at the British foreign office said they were aware of the reported video, but offered no further comment.

If the deaths are confirmed, it would be the biggest single loss of British lives in the Iraq war since it started in March 2003. The previous high was eight.

In a statement on an Islamic Web site, Ansar al-Islam (search) claimed its fighters tracked the Hercules C-130 (search) aircraft, "which was flying at a low altitude, and fired an anti-tank missile at it." The plane, carrying 10 people, was flying from Baghdad to the town of Balad, where the U.S. military has an air base.

"Thanks be to God, the plane was downed and a huge fire and black clouds of smoke were seen rising from the location of the crash," said the statement posted Sunday.

A spokesman for Britain's Ministry of Defense said he could not confirm the claim by the group, which has been linked to Al Qaeda (search).

"People on the ground are investigating," he said on condition of anonymity.

British Defense Secretary Geoff Hoon said nine British air force personnel and one soldier were missing and believed killed in the crash.

Capt. David Orwin, a British military spokesman in the southern Iraqi city of Basra, told the Press Association news agency that the crash site had been secured by U.S. and British forces.

A senior U.S. military officer in Iraq said the Royal Air Force plane crashed 25 miles northwest of Baghdad, and the wreckage was scattered over a large area. The Ministry of Defense said the crash occurred 19 miles northwest of the Iraqi capital.

Ansar al-Islam and other insurgent groups are known to operate in the area, and insurgents have fired at coalition aircraft before. Several thousand surface-to-air missiles disappeared from Iraqi military arsenals after the collapse of Saddam Hussein's regime, and many of them are believed to have fallen into the hands of insurgents.

Britain, America's top ally in the coalition, has 9,000 troops in Iraq, mostly in the south of the country near the city of Basra. British officials have not said why the Hercules was flying north of Baghdad.

"It is the largest single loss of British service lives since the military action began almost two years ago," Straw told British Broadcasting Corp. radio. "Our hearts go out to the families and comrades of those who were killed and those injured."

Prime Minister Tony Blair paid tribute to the casualties in a televised speech Sunday.

"This country and the wider world will never forget them," Blair said Sunday.

One of the dead was a serviceman with joint British-Australian citizenship, Flight Lt. Paul Pardoel, the Australian government said.

The British military has reported 76 deaths since the war started. Eight British troops died with four American crewmembers when a U.S. helicopter crashed in Kuwait on March 21, 2003.

The Royal Air Force flies several versions of the American-built C-130 Hercules aircraft, which is used to carry troops, passengers and freight.

The older C-130K model has a crew of five or six and carries up to 128 troops. The newer C-130J version has a crew of three and can also carry up to 128 infantry.

The RAF has about 60 Hercules aircraft, and about half of them are newer planes.

Military expert Air Vice-Marshall Tony Mason said the fact that the wreckage was widely scattered indicated the Hercules may have been shot down.

"The first statement said the crash site covered a wide area, which suggests impact in the air rather than the ground," Mason told the BBC. "My concern is that at the moment it could very well be hostile action."