Syrian forces advances inside Palmyra
Syrian forces have retaken six rebel-held areas in eastern Aleppo.Reuters

Syrian regime forces, with the backing of Russian air raids, retook the ancient city of Palmyra from the Islamic State group, Syrian state TV reportedly said Sunday. The extremist group had captured the city, recognised as a world heritage by UNESCO, May last year. 

President Bashar al-Assad's forces regained control over majority of the region in Palmyra, but clashes were underway Sunday morning around the prison and inside the airport in the eastern part of the city, Reuters cited the Britain-based Syrian Observatory for Human Rights (SOHR). 

Russia carried out around 40 air strikes on at least "158 terrorist" positions from Friday to Saturday, Agence France-Presse reported, citing Russian defence ministry. Russia , while withdrawing its forces from Syria, said it will continue air strikes against ISIS and other rebel groups in the country.

At least 188 troops and militiamen were reportedly killed in the battle with ISIS, which lost as many as 400 of its militants. "That's the heaviest losses that IS has sustained in a single battle since its creation" in 2013, SOHR director Rami Abdel Rahman told AFP.

While majority of the Islamic State group's militants have retreated east, there are others who are still inside the city. "A handful of IS fighters are refusing to leave the city and seem to want to fight on to the bitter end," Abdel Rahman said. 

By recapturing Palmyra, the military would be able to launch offencive against ISIS in Raqqa and Deir al-Zor, Reuters cited a statement from the army general command. Palmyra would act as "a launchpad to expand military operations" against ISIS in two provinces, it said.

"This achievement represents a mortal blow to the terrorist organisation and lays the foundation for a great collapse in the morale of its mercenaries and the beginning of its defeat," the statement read.