Insurgents ambushed an Iraqi army patrol north of Baghdad on Saturday, killing 19 soldiers in a well-planned attack, a day after the Pentagon announced 10 US Marines were killed by a bomb west of the capital.
The Iraqi soldiers were travelling in a five-vehicle patrol near Baquba, 60 km (40 miles) from Baghdad, when they were hit by a roadside bomb. Immediately afterwards, gunmen opened fire in what police described as a well-planned assault.
Police sources said 19 soldiers were killed and that they were all from southern Iraq where the population is largely Shia Muslim, potentially adding a sectarian element to the attack.
The deaths come amid a rise in insurgent violence ahead of elections set for December 15, and amid growing tensions between Iraq's Muslim sects. In a move that could aggravate those tensions, the country's top Shia cleric has urged Shia to turn out and vote for religious candidates on election day.
The attack in Baquba, where there has been a surge in guerrilla activity over the past three weeks, followed the assault on the Marines near the former rebel city of Falluja on Thursday, the deadliest attack on US troops for four months.
The Marines were on a foot patrol near a factory when they were struck by a bomb made out of several artillery shells strung together, the Marine Corps said. The deaths raise to more than 2,120 the number of US troops to have died in the war.
Al Jazeera broadcast a video on Saturday by a group called the Islamic Army in Iraq which the Arabic television channel said showed an explosion against a US patrol near Fallujah.
It was not immediately clear whether the group claimed the attack which killed the 10 US Marines.
The brief video shows a Humvee, flanked by troops travelling slowly down a street when a huge explosion engulfed the vehicle and sent bystanders fleeing the scene.
Al Jazeera said the video's authenticity could not be verified.
US commanders have said they expect an increase in violence in the build up to the election.