Syrian government troops entered the last Islamic State group stronghold in the country's Homs province on Friday after jihadists began withdrawing, a monitor said.

Al-Sukhna, some 70 kilometres (45 miles) northeast of the famed ancient city of Palmyra, is the last town on the road to the eastern city of Deir Ezzor, where a government garrison has held out under IS siege since early 2015.

The Syrian Observatory for Human Rights, a Britain-based monitor, earlier reported clashes on the city's outskirts and said government troops were firing artillery and rockets at IS positions.

By early evening, the monitor said government forces had entered the southwestern part of the town.

"The Islamic State organisation has carried out successive withdrawals from the town," it added.

"Regime forces have line-of-fire effective control of the town after the withdrawals," said Observatory director Rami Abdel Rahman.

He said the streets were reportedly empty, but it was unclear if pockets of IS fighters remained.

Since May, Syria's army has been conducting a broad military campaign with Russian support to recapture the vast desert that separates the capital Damascus from Deir Ezzor and other towns along the Euphrates Valley.

Already defeated in its Iraqi bastion of Mosul, IS is facing multiple assaults in Syria.

The US-backed Syrian Defence Forces now control more than half of its most important remaining stronghold Raqa.

Source: AFP