A suicide bomber crashed his vehicle into a US military convoy west of Baghdad on Thursday, the military said.

The explosion scattered debris into an area where troops were concentrated.

The wounded were taken to a military hospital by helicopter - four of them are believed to be in a serious condition.

Additionally, the US military on Friday announced that one of its soldiers had gone missing.

The US military said in a statement the soldier went missing when the car bomber detonated his vehicle. It did not elaborate.

"A multinational divison Baghdad soldier has been reported as Duty Status Whereabouts Unknown (missing) following an incident reported yesterday," the statement said.

Earlier on Thursday, the military had announced the death of three other soldiers in other attacks.

At least 25 US servicemen have died in Iraq since the start of the month.

The latest fatalities took the US military's losses since the March 2003 invasion to 2,675, according to an AFP news agency count based on Pentagon figures.

Trenches

In other developments, Iraq's government said on Friday that it will ring Baghdad with trenches in an attempt to restrict movements of insurgents.

 

The new security measures were spelled out by Brigadier-General Abdel Karim Khalaf of Iraq's interior ministry.

 

"We will surround the city with trenches," he said.

 

He said checkpoints will be set up on the 28 roads on which access will be allowed.

 

"This way we will have a better control of movements, including those of insurgents."

 

Baghdad has a circumference of 80km and observers noted that an operation of this scale would take months to  complete.