An Iraqi militant group has claimed responsibility for bringing down an RAF Hercules transport plane, killing 10 troops.

The Ansar al-Islam group said in a statement posted on an Islamic Web site that its fighters tracked the aircraft, "which was flying at a low altitude, and fired an anti-tank missile at it". "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.

The plane was flying from Baghdad to the town of Balad, a US military official said.

The wreckage of the Hercules is scattered over a large area, suggesting a mid-air explosion, a senior US military officer in Iraq said.

British and US military officials have not said what they think caused the crash, which occurred about half an hour after polls closed in Iraq's elections.

Established after the 9/11, attacks, Ansar al-Islam is one of Iraq's older extremist groups and it has been linked to al Qaida.

Prime Minister Tony Blair confirmed there were deaths in the crash, but did not say how many as he paid tribute to the casualties in a televised speech praising Iraq's election.

One of then 10 men who died in the Hercules became the first Australian serviceman killed on military duty in Iraq.

Flight Lieutenant Paul Pardoel, 35, a father of three from Victoria, had joint British and Australian citizenship.

Pardoel formerly served in the Royal Australian Air Force but was serving with the RAF at the time of his death. The Australian Defence Force announced the death in a statement.

My thoughts and prayers go out to all of those effected by this latest tragedy.