38 militants killed in air strikes over central Syria

At least 38 fighters from the Islamic State group have been killed over the last 24 hours as Syrian government warplanes bombarded the group's strongholds in central Syria, a monitoring group said.

Monday's strikes hit Palmyra and two other towns in Homs province, Syrian Observatory for Human Rights' director Rami Abdelrahman said on Tuesday.

The Syrian air force has been increasing its strikes against IS in recent days as it received reinforcements from Russia, he said.

"The number of raids is growing and the strikes are more precise after the Syrian air force received arms and more efficient planes from Moscow," said Abdelrahman, whose UK-based group relies on broad network of civilian, military and medical sources inside Syria.

Russia has been dramatically increasing its forces at an air base south of Latakia, a stronghold of Syrian President Bashar al-Assad, including positioning combat planes and helicopters as well as tanks and accommodation blocks.