An explosion targeted a US patrol in a Baghdad suburb on Thursday, hitting a military vehicle and inflicting American and Iraqi casualties, witnesses and a US officer said.

The blast was another sign that hit-and-run attacks against US and British forces were becoming more frequent and more sophisticated and could pose a serious challenge to the coalition trying to rebuild Iraq after Saddam Hussein's fall.

The witnesses said a Humvee military car was hit in the 9 am (0500 GMT) attack on a road leading to Baghdad airport in the Amiriyah neighbourhood. They said they saw blood in the vehicle.

An Iraqi civilian car carrying electricity workers was also damaged in the attack. One occupant was killed and another badly wounded. Three passers-by were also wounded.

Captain Sean McWilliams of a tank company attached to the 82nd Airborne told reporters on the scene that the attack caused an unspecified number of U.S. casualties, who were taken to hospital. He did not know the extent of their injuries.

"It was some explosive device. We don't know what type. We have no reports of bullets, just shrapnel," McWilliams said.

"The point we want to drive home to everybody is that attacks like this won't deter us from our mission. All the people wanted to do here was stop the transition to a new democratic Iraq, and they're not going to succeed in that."

US troops have come under attack almost daily over the past month in mainly Sunni central Iraq and 19 have been killed since war was declared over on May 1. Washington blames the attacks on Saddam loyalists.

Six British soldiers were killed by Iraqi civilians on Tuesday in the Shi'ite Muslim town of Majjar.

It was the worst single attack on British and U.S. forces in Iraq since March 23, three days after they went to war.

The Qatar-based al-Jazeera television said on Wednesday it received a statement from a group calling itself Mujahidoo al- Ta'ifa al-Mansoura (Muslim Fighters of the Victorious Sect) claiming responsibility for several attacks on US forces in Iraq as well as the cassette of one of its attacks.

The statement "urged Iraqis to stay away from US forces for their own safety because the group planned further attacks in the near future", Jazeera said, showing a copy of the brief statement in Arabic.

Jazeera said the group did not clarify the date of the attack in a Baghdad suburb, which it said was carried out by one of its units, the Martyr Khattab group, or whether there were any casualties.

A US military statement said one Marine died and two others were injured on Wednesday when their light armoured vehicle rolled over on a road near Hilla town south of Baghdad.

The Marines of the 1st Marine Expeditionary Force were part of a quick reaction force responding to comrades who were engaged by "hostile forces", the statement said. The accident occurred prior to arriving at the ambush site.

Three Marines were also wounded as a result of the ambush, it added.