By Peter Beaumont, The Guardian: An Iranian-backed militia in Iraq has accused the US and Israel of involvement in an alleged drone strike on a munitions warehouse near Baghdad last week, the latest in a series of mystery explosions at similar bases.

The claim came after the findings of an Iraqi government inquiry into the huge blast at the facility of the Popular Mobilisation Forces (PMF) were leaked.

A spokesman for the PMF said it had intelligence that showed the US had brought in four Israeli drones earlier this year to work as part of the US fleet in Iraq and target militia positions in the country.

Abu Mahdi al-Muhandis said the PMF would from now on use “all means at its disposal to deter and prevent such attacks on our positions”.

His comments followed another explosion on Tuesday, this time at a Shia militia base north of Baghdad which was again blamed on an aerial attack.

The explosions have encouraged a wealth of competing theories as to those responsible including Israel, Islamic State militants or rival Iraqi factions.

Tellingly, however, an official report leaked to the Associated Press said investigators believed the explosions at the al-Saqr military base on 12 August were the result of a drone strike. The blasts killed one civilian and wounded 28 others.

The base housed weapons both for the Iraqi federal police and the PMF, which was heavily involved in the fight against Isis alongside Iraq’s official security forces.

The al-Saqr incident was the fourth in a series of explosions at similar facilities in the last month. Two Iranian military engineers were allegedly killed in one blast on 19 July.

That attack, on the al-Shuhada base of the PMF, was also initially blamed on a drone strike amid reported allegations that the facility had recently received a shipment of Iranian ballistic missiles.

After a national security meeting last week, the Iraqi prime minister, Adel Abdul-Mahdi, ordered a ban on all military flights throughout the country, unless specifically authorised by the defence ministry.

Amid speculation in Israeli and Iraqi media reports that Israel may have expanded its targeting of Iranian-backed proxies from Syria to Iraq, Israel’s prime minister, Benjamin Netanyahu, said on Monday: “Iran has no immunity, anywhere ... We will act and currently are acting against them, wherever it is necessary.”

An American official, however, said the US had no evidence or credible intelligence that Israel was behind the two most recent blasts.

The series of explosions, however, have exacerbated the already fraught perception in Iraq that it risks being sucked into the escalating tensions between the US and Iran.

First published in The Guardian.

Peter Beaumont is a senior reporter on the Guardian's Global Development desk. He has reported extensively from conflict zones including Africa, the Balkans and the Middle East and is the author of The Secret Life of War: Journeys Through Modern Conflict