Blast latest in series of explosions targeting sites belonging to groups under umbrella of Popular Mobilisation Forces.

A blast has hit an arms depot belonging to Iranian-backed paramilitaries north of Baghdad, according to media reports.

The site struck on Tuesday is close to the Balad Air Base, which hosts US forces and contractors and is located about 80km north of the Iraqi capital, in the Salahuddin province.

The explosion is the latest in a series of mysterious blasts in recent weeks, targeting bases and warehouses belonging to groups under the umbrella of militias known as the Popular Mobilisation Forces (PMF). Some have been blamed on drone attacks, others on faulty storage.

There was no immediate claim of responsibility for Tuesday’s explosion.

A military official told Reuters news agency the intended target was the militia’s position near the base, while a paramilitary source said his group’s weapons depot was specifically targeted by an aerial bombardment.

Witnesses told Reuters the explosion caused stored rockets to fly into nearby orchards and into Balad base itself.

Separately, a police source told Reuters news agency that the cause of the explosion was still unclear, adding that two fighters were killed and five were wounded.

Last week, at least one person was killed and 29 others wounded after homes were damaged by an explosion at a weapons depot in Baghdad.

Police at the time attributed the explosion to poor storage and high temperatures, but a government investigation is under way.

Last week, Iraqi Prime Minister Adel Abdul Mahdi banned unauthorised flights throughout the country.

Some analysts have suggested the strikes might have been carried out by Israel, which last year signalled that it could attack suspected Iranian military assets in Iraq, as it has done with scores of air raids in Syria.

“Iraq’s air defences have very high capability, but one thing they couldn’t detect is an advanced Israeli air attack,” Baghdad-based security analyst Hisham al-Hashimi, who advises the government, told Reuters.

Israeli officials have suggested recently they view Iraq, whose main ally is Israel’s regional foe Iran, as more of a threat than in recent years, but have not directly commented on the recent blasts at PMF sites in Iraq.