Russian air strikes force Islamic State retreat in Syria's Palmyra: monitor

The militants were now fighting in orchards on the fringe of Palmyra, the British-based Syrian Observatory for Human Rights said.

Russia's Defence Ministry said its jets had launched 64 strikes and killed more than 300 militants during the operation, backing up the Syrian army.

Islamic State fighters had gained control of some oil and gas fields around the city during their advance which started on Thursday, the monitor said. They had also been pushing towards the nearby T4 air base - used by Russian forces supporting the Syrian army.

It was not immediately clear who now controlled the fields, including al Mahr and Jazal.

The city had been recaptured from the militants last March, in what was hailed as a major victory for the government and the biggest reversal for Islamic State in Syria since Russia's intervention, which turned the tide of the conflict in Assad's favor.

(Reporting by Suleiman Al-Khalidi; Additional reporting by Jack Stubbs in Moscow; Editing by Andrew Heavens)