Russia claimed on Friday to have killed several top commanders of the Daesh group in an air strike in Syria, including the US-trained "minister of war" who has a $3 million bounty on his head.

"As a result of a precision air strike of the Russian air forces in the vicinity of Deir Ezzor city, a command post, communication centre and some 40 Daesh fighters have been killed," the Russian defence ministry said in a statement posted on Facebook.

"According to confirmed data, among the killed fighters are four influential field commanders including Deir Ezzor emir Abu Mohammed Al Shimali," the ministry said.

Gulmurod Khalimov, who is known as the Daesh group's minister of war and the highest-ranking defector from ex-Soviet Tajikistan, suffered a "fatal injury," it added.

Reports of Khalimov's death have surfaced before, and the Tajik interior ministry said it could not immediately confirm the claim. "We are working with our Russian colleagues to obtain reliable information," a spokesman told.

But a spokesman for the Tajik security services, speaking to AFP, suggested that "this time around" he might have been killed.

"We're checking the information," he said.

In 2016, the United States offered a $3 million bounty for information leading to Khalimov's location or arrest. Russia's SU warplanes dropped "bunker buster" bombs on the fighters as they were meeting near Deir Ezzor to discuss how to respond to the advance of the Syrian army, Moscow said.

Backed by Russia, Syrian troops on Tuesday broke through a years-long siege imposed by Daesh militants on tens of thousands of civilians in Deir Ezzor.

The Times reported in April that Khalimov had been killed in an airstrike.

Source: Khaleej Times