Russian air strikes have killed 18 ISIL group fighters in central Syria, including near the historic city of Palmyra, over the past 24 hours, a monitor said on Friday.

Russian air strikes have killed 18 ISIL group fighters in central Syria, including near the historic city of Palmyra, over the past 24 hours, a monitor said on Friday.

The Britain-based opposing Syrian Observatory said European members of ISIL were among the dead in the strikes around the town of Sukhna and near Palmyra in the central province of Homs.

A key ally of the Syrian government, Russia began carrying out air strikes in the country in late September.

On Thursday, it said it had carried out more than 50 raids over two days targeting ISIL 'jihadists' near Palmyra, which government forces recaptured from the extremist group in March.

"The Russian air force has increased the intensity of its strikes against targets of the armed units of international terrorist organizations near the city of Palmyra," the ministry said in a statement Thursday on its Facebook page.

Six Tupolev bombers flew out of an airbase in Russia on Thursday morning and conducted strikes east of Palmyra, near the cities of Arak and Sukhna, as well as in the Homs region, the statement said.