An unmanned aircraft dropped explosives on a base belonging to Iran-linked Shia paramilitary groups in northern Iraq on Friday, killing at least one person, the army and paramilitary sources said.
The Iraqi military said in a statement a drone had dropped a grenade onto the base in northern Salahuddin province, wounding at least two people, but gave no further details.
Paramilitary sources in the area and a Baghdad-based paramilitary leader said one person had been killed in the attack, which took place early on Friday.
There was no immediate claim of responsibility.
A security source said two explosions hit the base, one targeting an ammunition depot belonging to an Iran-backed group.
The Pentagon denied that US forces were involved in the attack, after at least one Saudi-based news channel reported US strikes on the base.
The incident took place amid heightened tension between the United States and Iran.
Iraq is seen as a potential arena for any violent regional confrontation between the two foes because of the presence of Iran-backed Shia Muslim paramilitary groups operating in close proximity to bases hosting US forces.
Islamic State militants, also enemies of the Shia paramilitaries, operate in the area where the base is located and in many remote areas of northern Iraq, despite the group having lost its sway over territory.
It has claimed attacks against Iraqi forces in recent months.
Several Iraqi bases hosting US forces were hit by a number of rockets a few weeks ago in unclaimed attacks in which no one was hurt.
Washington is pressing Iraq's government to rein in Iran-backed paramilitary groups which it says pose a threat to US interests in Iraq.
The United States has blamed Iran for attacks on several oil tankers in the Gulf. Tehran denies any involvement.