Baghdad - United States forces killed 13 insurgents in an air strike on two suspected foreign fighter safe houses west of Baghdad on Thursday, the US military said.

It said the operation targeted a "senior foreign fighter facilitator" northeast of the town of Ameriya, near Falluja, in an area where there is a strong presence of Sunni insurgents.

"This operation significantly reduces foreign fighter facilitators' ability to operate inside Iraq," it said in a statement.

Five suspects were detained along with a cache of armour piercing ammunition, which can be used to make roadside bombs.