Deaths peaked in May when 126 American soldiers died in coalition assaults on insurgent strongholds. The second half of the year saw violence drop dramatically with the American surge of 30,000 extra troops and a freeze on activities by some militias.

As of last night in Baghdad, 21 deaths were reported in December, one more than in February 2004, the month with the lowest death toll.

The 899 American troop deaths in 2007 surpassed 2004 when 850 US soldiers were killed.

The US military deaths are dwarfed by Iraqi civilian casualties, although the fluctuations show the same pattern. It is difficult to obtain accurate figures on civilian casualties but the Associated Press said Iraqi civilian deaths peaked in May with 2,155 killed, falling to 718 in November and 710 in December.

Over the year, 18,610 Iraqis were killed. In 2006, the only other full year an AP count has been made, 13,813 civilians were killed.

The civilian toll was compiled by AP from hospital, police and military officials, as well as accounts from reporters and photographers. Insurgent deaths were not included. Other counts differ and some are much higher.

The US military commander in Iraq, General David Petraeus, yesterday used the more recent statistics to give an upbeat assessment of the security situation in Iraq.

Overall violence across the country was down roughly 60% since June, he said, and the favourable security situation would allow some US troops to return home during the coming year as responsibilities were handed over to the Iraqi army.

Petraeus also drew attention to the significance of Sunni tribal leaders transferring allegiance to the Iraqi government. In the western province of Anbar, and in Baghdad, coalition of Iraqis known as Awakening Councils or Concerned Local Citizens groups that receive US money and expertise have been joined by Sunni Arabs previously opposed to the invasion. Their coalition in Anbar province, a Sunni stronghold, now numbers 70,000 fighters.

These Sunnis are threatened by Osama bin Laden in a video released on Saturday that is the fifth message attributed to him in 2007.

Bin Laden warned Sunni Arabs who had joined the US initiatives that they had "betrayed the nation and brought disgrace and shame to their people. They will suffer in life and the afterlife."

Along with the increase in American troops, Iraq's lessening violence has been attributed to a freeze on activities by the Mahdi Army, the militia of radical Shia cleric Muqtada al-Sadr.

British military casualties were also higher in 2007 than 2006. According to Ministry of Defence statistics released at the end of November, 46 soldiers had died in 2007 compared with 29 the year before.

Like America, the first half of the year was worse for British forces than the second half. Of the 46 deaths in total for 2007, 29 were in the first six months of the year as opposed to 17 in the second half.

Unlike the American figures, UK military deaths in 2004 were the lowest since the beginning of British operations in Iraq, known as Operation Telic, in March 2003.

In total, 174 British personnel have died in Operation Telic.