Islamic State [IS] group said it has shot down a Syrian regime warplane near the history city of Palmyra.

The extremist group's Amaq news agency said on Saturday that the militants downed the jet near the Jazal oil fields west of the city, which is home to fame 2,000-year-old ruins.

Meanwhile Britain-based Syrian Observatory for Human Rights also reported that a regime jet crashed in the Jazal area.

It said IS militants were attacking government positions four kilometres [2.5 miles] from Palmyra, which the government recaptured from the extremist group to great fanfare in March.

The activist-run Palmyra Coordination Committee said the jet was a MiG-23.

Fifteen Syrian regime fighters were killed in an IS ambush near the Mahr oilfield on Friday.

Amaq news agency distributed a video that showed what it said were Syrian soldiers fleeing their positions west of Palmyra.

The IS assault near the ancient city in Homs province took up the regime's death toll since Thursday to 49.