One fighter was killed and another heavily wounded, an official statement said.

Iraq's Hashed al-Shaabi accused Israel of a deadly drone attack on Sunday that left one paramilitary fighter dead, the first time the force has directly blamed the Jewish state for such a raid.

The attack struck a position held by Brigade 45, a Hashed al-Shaabi unit based near Al-Qaim about 15 kilometres from Iraq's western desertic border with neighbouring Syria.

It is the latest in a string of suspicious explosions and drone sightings at Hashed bases that have sparked concern of a possible proxy war between Iran, the US, and Israel on Iraqi soil -- or in its airspace.

"As part of the string of Zionist attacks on Iraq, the evil Israeli crows have returned to target the Hashed al-Shaabi, this time with two drones inside Iraqi territory," the statement said.

It said one fighter was killed and another heavily wounded, revising an earlier toll of two dead.

"This blatant attack came with air cover over the area from American planes, in addition to a large balloon to monitor the area near the site of the incident," the force added.

Blasts have been reported at four other Hashed bases since mid-July, and a fifth unit near Baghdad said on Thursday it had shot at a surveillance drone flying over its position.

The Hashed was established in 2014 from disparate armed groups and volunteers, most of them Shiite Muslims, to fight the Islamic State group.

The network has received Iranian training, but it operates officially under Iraq's armed forces and uses military unit names.

'Final warning'

Brigade 45, for example, is one of several units made up of Kataib Hezbollah fighters, designated by the US as a "foreign terrorist organisation".

The group issued a "final warning" to the US last week over previous purported attacks.

"We issue a final warning to the American enemy that any new targeting of any Iraqi positions will be met with a tough, categorical response," it said in a statement.

A military source from Kataib Hezbollah told AFP on Sunday that the fighter killed in the drone attack, Abu Ali al-Dabi, was a member of the unit's rocket squad.

"He fought in Syria and was previously detained by the Americans," the source said.

Sunday's statement was the first time the Hashed formally accused Israel of involvement in a specific incident.

Its deputy leader Abu Mehdi al-Muhandis, whose virulent anti-Americanism as a militia leader earned him a US terror blacklisting, issued a statement last week fingering Washington as "the first and last entity responsible".

He said Israeli drones had entered Iraqi airspace but did not explicitly blame them for an attack at the time.

The Iraqi government is also carrying out investigations into the incidents but has yet to publish results.

The Pentagon has denied involvement, and US officials have told the New York Times that Israel has carried out multiple strikes in Iraq this month.

'Signal to Iran'

Israel has not claimed responsibility but Prime Minister Benjamin Netanyahu has hinted at involvement, saying his country would "act against (Iran) whenever necessary".

"From Israel's point of view, Iran's assets in Iraq are part of a broader strategy that aims to establish a military presence and strike capability in Iraq, Syria and Lebanon," said Fanar Haddad, an Iraq expert at the National University of Singapore.

Israel has carried out several hundred bombing raids against Iranian forces and their allies in neighbouring Syria.

"The attacks in Iraq are a signal to Iran that Israel is willing and capable of extending its relentless campaign of airstrikes in Syria to Iraq and beyond," Haddad added.

On Sunday, the head of Lebanon's powerful Hezbollah movement said Israel was behind a drone attack on the group's stronghold in a southern suburb of Beirut.