BEIRUT: Fierce battles between Syrian regime forces and the Islamic State group in eastern Syria have left 34 fighters dead in 24 hours, a monitor said Friday.

The Syrian Observatory for Human Rights said 19 pro-government forces and 15 IS extremists had been killed since clashes began late Wednesday in the city of Deir Ezzor and around its nearby military airport.

The head of aerial defense at the airport — one of the few areas left in regime hands in Deir Ezzor province — was killed in the fighting, the Observatory said.

Four government soldiers were beheaded by IS Thursday as the radicals seized a key checkpoint in the city near the air base.

“An IS suicide bomber detonated himself by the checkpoint, which IS then seized,” said Observatory director Rami Abdel Rahman.

“Seizing the checkpoint gets them closer to the military airport.”

Abdel Rahman said fighting continued into Friday morning with both sides shelling positions on the outskirts of Deir Ezzor city.