Russian helicopters pounded jihadist positions around the ancient city of Palmyra on Tuesday as Syrian troops pressed a ground advance, a monitoring group said. 

"Russian helicopters and warplanes, that are likely Russian, are bombarding Islamic State group positions near Palmyra," said Syrian Observatory for Human Rights director Rami Abdel Rahman.

The strikes came a day after Russian President Vladimir Putin ordered  the pullout of the "main part" of his forces from the war-torn country.