American and Iraqi troops have launched a new counterinsurgency operation in western Iraq.

A U.S. military spokesman Saturday, said about 500 U.S. Marines and 100 Iraqi soldiers are carrying out the offensive in Iraq's western Anbar province.

They say 22 suspected insurgents have been detained since the operation began southeast of Falluja Thursday.

It is the fourth major counterinsurgency operation in Anbar province in the past month. Military officials say the province stretching from the Syrian border to just west of Baghdad is a conduit for foreign militants entering Iraq.

Meanwhile, Iraqi and U.S. officials say they are concerned over a series of attacks on foreign diplomats in recent days. Several high-level Arab officials have been targeted and Egypt's ambassador Ihab al-Sherif was assassinated earlier this week.

Some information for this report provided by AP and Reuters.