The explosion hit the Kalsu military base in Babylon province south of Baghdad, where Iraq's Popular Mobilisation Forces, or Hashed al-Shaabi, is stationed.

It comes days after Iran launched an unprecedented assault on Israel which reportedly responded with a drone strike on the Islamic republic, amid tensions fuelled by the Gaza war.

The Iraqi security forces media unit said "an explosion and a fire" hit the Kalsu base in the early hours of Saturday, leaving one person dead and eight wounded.

Air defence command reported "no drones or combat aircraft in the airspace of Babylon province before or during the explosion", it added in a statement.

An interior ministry official had initially reported an "aerial bombing" on the site.

In a statement, Hashed al-Shaabi said an "explosion" had inflicted "material losses" and casualties, without giving a number.

The group confirmed its premises on the military base had been hit and that investigators had been sent to the site.

There was no immediate claim of responsibility.

Responding to questions from AFP, the security sources did not say who may have been behind the attack.

"The explosion hit equipment, weapons and vehicles," said the interior ministry source.

- 'Odious crime' -

Shortly after the explosion, the US military said its forces were not behind a reported strike in Iraq.

"The United States has not conducted air strikes in Iraq today," US Central Command (CENTCOM) posted on social media platform X, adding that reports that American forces had carried out a strike were "not true".

The Iraqi military official, who spoke on condition of anonymity due to the sensitivity of the subject, said the overnight explosion had occurred in "warehouses storing equipment".

When reached by AFP, the Israeli army said it "does not comment on information published in foreign media".

The Hashed al-Shaabi is an integral part of the official Iraqi security apparatus under the authority of the prime minister.

It brings together several pro-Iran armed factions, some of which have also carried out dozens of attacks in Iraq and Syria against US forces deployed as part of an international anti-jihadist coalition.

"We will retaliate against whoever is behind this aggression," Hashed commander Abu Alaa al-Walai wrote on X, formerly Twitter. "Those involved in this odious crime will pay the price."

On Friday, strikes blamed on Israel targeted a military base near the city of Isfahan in central Iran.

The explosion came in response to Tehran's unprecedented attack on Israel last weekend, in retaliation for a deadly strike on Iran's embassy in Damascus.

Iraq's foreign ministry expressed "strong concern" on Friday over the blast in Iran, warning of the "risks of military escalation which threatens security and stability in the region."

"This escalation must not be allowed to divert attention from what's happening in the Gaza Strip," it said.

Iraqi Prime Minister Mohamed Shia al-Sudani is in Washington, where he met US President Joe Biden this week.

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