WASHINGTON (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 (March 11), two US officials told Reuters, citing preliminary information.

The officials said it was too early to assign blame, but any indication that Iran-backed militia were responsible could ignite a new round of military escalation between the United States and Iran.

The officials, speaking on condition of anonymity, declined to quantify the number of troops and military contractors among the dead and wounded and noted that the information was just coming in and could change.

Initial battlefield reports often contain inaccuracies.

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 US forces and the area around the US 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 US strikes against it in Iraq and Syria.

Earlier this year, 11 Iranian ballistic missiles struck the al-Asad air base in Iraq after the United States killed a top Iranian general.

The Iranian attack led to more 100 American service members being diagnosed with mild traumatic brain injuries.