Three Task Force Marine soldiers were killed Saturday when a roadside bomb struck their convoy south of Baghdad, according to a brief statement that provided no more details.

One Multi-National Division Baghdad soldier was killed and another wounded Monday when their vehicle was targeted by an armour-piercing explosively formed penetrator, or EFP, in a western section of the capital, the military said separately.

The US military has accused Iran of supplying Shia extremists with EFPs to step up attacks against American forces. Tehran denies the allegations.

The deaths raised to at least 3,678 members of the US military have died since the Iraq war started in March 2003, according to an Associated Press count.

Five American soldiers have died in Iraq, four of whom were killed on Monday in the flashpoint city of Baquba in the troubled province of Diyala, the US military announced.

"Four US soldiers were killed today in Baquba. There were also 12 soldiers injured," a military spokesman told AFP in an email following a query about a single attack in the restive town north of Baghdad.

Thousands of US and Iraqi forces have been pressing a massive assault in Diyala, one of the country's deadliest regions, and its provincial capital Baquba since June in a bid to flush out al-Qaeda-linked militants.

US forces claim to have killed and captured dozens of militants, but senior commanders have said that most of the top al-Qaeda leaders in the area fled before the assault began.

The US military said that another American soldier was killed and two others were wounded in an eastern part of the war-torn Iraqi capital on Sunday.

The latest deaths took US losses in Iraq since the March 2003 invasion to 3,670, according to an AFP count based on Pentagon figures.

At least 19 soldiers have been killed in August.