Beirut (AFP) - Air strikes on a convoy of the Islamic State group killed at least 40 jihadists in central Syria at the weekend, a monitoring group said Sunday.

The Britain-based Syrian Observatory for Human Rights said unidentified warplanes hit the 16-vehicles motorcade overnight between Saturday and Sunday in Hama province, killing the jihadists.

The Observatory, which monitors the war in Syria and has a network of sources on the ground, was not immediately able to say whether the raids were carried out by Russian warplanes or Syrian regime ones.

"But they don't belong to the coalition led by Washington," said Observatory chief Rami Abdel Rahman.

Charred bodies of IS fighters were found at the scene, he added.

Syrian regime aircraft bombard almost daily the eastern countryside of Hama where IS has positions.

Abdel Rahman said the convoy was hit as it was heading from the self-declared IS capital of Raqa in northern Syria to the Hama countryside.

Russia, a key ally of the Syrian regime of President Bashar al-Assad, has been carrying out a campaign of air strikes against his opponents since September 30.

Last year, a US-led coalition launched an air campaign against IS which controls swathes of Syria and neighbouring Iraq.