Russia's air force hit 63 targets in Syria in the past 24 hours, the defence ministry said Sunday, as Moscow intensifies a campaign it says is aimed against ISIS insurgent group.

"Su-34, Su-24M and Su-25SM planes carried out 64 sorties from the Hmeimim airbase against 63 targets in the provinces of Hama, Latakia, Idlib and Raqa," the defence ministry said in a statement, adding the airstrikes had destroyed 53 positions used by the "terrorists".