US forces killed 13 insurgents in an air strike on two suspected safe houses of foreign fighters west of Baghdad on Thursday, the US military said.  
 
US aircraft used precision guided munitions during the morning raid and killed 13 terrorists near the Amiriya town west of Baghdad, the military said in a statement.

During the operation, US troops also detained five suspected terrorists and found a cache housing armor piercing ammunition, the statement said.

Meanwhile, four US marines were killed in the volatile area of Anbar province in two separate incidents, said the US military.

The marines assigned to Multi-National Force - West died on Wednesday from wounds sustained due to "enemy action", the military said in a statement.

Since the US-led war in Iraq broke out in March 2003, more than 3,100 US soldiers have been killed in Iraq, according to media count based on Pentagon confirmed figures.

(Xinhua News Agency February 9, 2007)