Russia laid bare its ambition to liberate Palmyra, suggesting its forces focus on the ancient Syrian city while leaving Raqqa to the US, as warplanes bombed Islamic State (Isis) positions in the area. Foreign Minister Sergei Lavrov implied there was a tacit consensus between Washington and Moscow that the US-led coalition contests with IS (Daesh) on the north-eastern flank while Kremlin-backed regime forces attack the group in the west.

"We are ready to coordinate our actions with the Americans, because Raqqa is in the eastern part of Syria, and the American coalition is mainly ... acting there," Lavrov was quoted as saying by Interfax news agency. "Perhaps, this is no secret, if I say that at some stage the Americans suggested performing a 'division of labour': the Russian Air Forces should concentrate on the liberation of Palmyra, and the American coalition with Russian support will focus on the liberation of Raqqa".

Meanwhile artillery fire and air strikes continued to target Isis militants in and around the Unesco World Heritage site. More than 200 shells and rockets fell on the city which was also hit by 80 air strikes on 14 March, the Syrian Observatory for Human Rights reported.

Ground forces were also reportedly advancing slowly west of Palmyra, gaining ground in clashes that saw six jihadists killed. Fighting in the area intensified last week rising concerns about the safety of Palmyra's archaeological treasures that have been already irreparably damaged by Isis's violence.

Freeing the ancient metropolis the jihadi group that deliberately damaged it by blowing up temples and shrines, would be a major propaganda coup Russian president Vladimir Putin, whose decision to intervene in Syria has drawn criticism over allegations of war crimes and high civilian casualties. Isis (Daesh) captured Palmyra in May 2015 and has since destroyed a number of classical monuments it deemed blasphemous symbols of ancient religions.