Islamic State fighters retreated from the Syrian city of Palmyra at dawn on Sunday, (11 December) after heavy air raids by Russia, just hours after they captured the ancient city, a UK-based monitoring group said.
"Intense Russian raids since last night forced IS out of Palmyra, hours after the jihadists retook control of the city," Rami Abdel Rahman, head of the Syrian Observatory for Human Rights said.
He added that the air strikes killed several jihadists in the desert city of Central Syria but could not give a specific number.
According to reports, the Syrian army also sent additional troops to Palmyra, reportedly diverting personnel from Aleppo, the BBC reported.
The jihadist group captured the Unesco world heritage site of Palmyra in May 2014 and were forced out in March 2016.