The Pentagon on Monday confirmed that a US air strike killed Daesh leader and spokesman Abu Mohamed al-Adnani in northern Syria last month.

"The strike near Al Bab, Syria, removes from the battlefield ISIL's chief propagandist, recruiter and architect of external terrorist operations," Pentagon press secretary Peter Cook said, using another acronym for Daesh group.

"It is one in a series of successful strikes against ISIL leaders, including those responsible for finances and military planning, that make it harder for the group to operate."

The August 30 air strike was conducted by a Predator drone, which fired a Hellfire missile at the car Adnani was traveling in.

Officials say Adnani was the main spokesman for Daesh, and he had played a major role during some of the group's most high-profile attacks over the past year, including in Paris, at the Brussels and Istanbul airports, at a cafe in Bangladesh, as well as the downing of a Russian airliner in the Sinai and suicide bombings at a rally in Ankara.

Cook has previously said Adnani had coordinated the movement of Daesh fighters, encouraged lone-wolf attacks on civilians and members of the military and actively recruited new Daesh members.

Soon after the strike against Adnani, Russia said it was responsible for his death, a claim Pentagon officials dismissed as a "joke."