WASHINGTON, March 11 (Reuters) -

Two American personnel and one from Britain were killed and about a dozen people were wounded when 15 small rockets hit Iraq's Taji military camp north of Baghdad on Wednesday, two U.S. officials told Reuters, citing early information.

The officials said it was too soon to assign blame. Any indication that Iran-backed militia were responsible could spark a new round of confrontation between the United States and Iran.

The last military escalation led to a U.S. strike in January that killed top Iranian general Qassem Soleimani, which, in turn, led Iran to fire missiles at a base in Iraq hosting U.S. forces, leaving more than 100 troops with brain injuries.

U.S. Secretary of State Mike Pompeo has argued the strike was necessary to deter Iran from additional attacks.

The Pentagon, State Department and White House did not immediately respond to requests for comment.

Earlier on Wednesday, the Iraqi military said no casualties had been reported in the attack.

Iran-backed paramilitary groups have regularly been rocketing and shelling bases in Iraq that host U.S. forces and the area around the U.S. Embassy in Baghdad.

The Kataib Hezbollah militia was blamed for an attack on a base last year which killed an American contractor, which led to retaliatory U.S. strikes against it in Iraq and Syria.

Syrian state media reported on Wednesday that unidentified jets hit targets southeast of a Syrian town along the border with Iraq.