Iraqi officials say a suicide attack west of the capital has killed at least six troops.

A police officer said the attacker on Saturday drove an explosive-rigged car Saturday into a military headquarters in the town of Garma, where government forces and allied militias have been battling Islamic State militants.

He said the dead included three soldiers and three militia members. Nine other troops were wounded.

A medical official confirmed the casualty figures. Both officials spoke on condition of anonymity as they were not authorized to release information.

Backed by airstrikes from the U.S.-led international coalition, Iraqi troops and their militia allies have been trying to dislodge the militants from Garma east of the IS-held city of Fallujah.

Security forces have reported slow progress in recent weeks.