Six U.S. soldiers and an interpreter were killed by a roadside bomb in western Baghdad on Saturday, the U.S. military said as a search for three abducted soldiers entered its second week on Sunday.

The soldiers and their interpreter had been uncovering caches of weapons, including grenades and small arms, as well as bomb-making equipment in the capital over the past week.

"Finding these weapons caches helps reduce the threat of insurgent attacks and continues to aid in providing a more secure and safe living environment for the Iraqi people," the military said in a statement.

More than 3,400 U.S. soldiers have been killed since the U.S.-led invasion to topple Saddam Hussein in 2003.

At least 70 U.S. troops have died so far this month as the U.S. military pours thousands of extra troops into the capital as part of a security crackdown seen as a last-ditch attempt to stop Iraq sliding into all-out sectarian civil war.

Fifteen soldiers have been killed in the past three days.

Thousands of U.S. troops are searching for three soldiers missing since an ambush south of Baghdad on May 12. Four U.S. soldiers and an Iraqi interpreter were killed in the attack.