Islamic State jihadists battled Syrian regime forces on Friday on the outskirts of Palmyra, the ancient town from which they were chased out eight months ago, rights observers said.

The jihadists have launched an offensive in recent days close to the town which is on UNESCO's world heritage list. They have now progressed "right up to the edge of the town," said Abdel Rahman, director of the Syrian Observatory for Human Rights.

Fierce fighting is continuing on the ground, while at the same time the Syrian airforce has launched air strikes against IS fighters, he said.

"The noise of fighting can be heard inside the town," added Rahman, whose organisation has civilian and military sources across Syria.

Since Thursday IS fighters had been only four kilometers (2.5 miles) from the town. "Today they launched a new attack and advanced," he said.

According to the Observatory, at least 49 pro-government force members have been killed by IS since Thursday in the offensive in the province of Homs, where Palmyra is situated.

They include 15 fighters killed in an IS ambush near the Mahr oilfield.

On Thursday IS fighters launched simultaneous attacks near the Mahr and Chaar oil and gas fields and elsewhere in Homs province, killing 34 members of pro-regime forces.

The Islamic State group seized control of several towns in the province including Palmyra in May last year including its ancient sites which they damaged extensively.

The Syrian regime controls most of Homs province but its troops are regularly attacked by IS fighters notably when they are in isolated areas, including in oil fields which are difficult to protect.

Source: AFP