Syrian regime 'completely encircle' IS in al-Mayadeen, despite 'mass escape' of jihadi leaders from city

Syrian regime troops have "completely encircled" a group of Islamic State group militants in the eastern city of al-Mayadeen, state media said on Sunday.

The city, which was once a military hub for IS, is now one of the group's last strongholds in eastern Syria's Deir az-Zour province.

Syrian regime troops entered the city that lies on the Euphrates River on Friday with other pro-Damascus forces advancing from other sides.

"Units of our armed forces with the allied forces continue their advance on a number of fronts and axes in Deir al-Zour and its countryside... and encircle [IS] terrorists in the city of al-Mayadeen," a military source told Reuters.

Syrian state news agency SANA confirmed that the militants' in the city were "encircled", although it also added there had been a "mass escape" of IS fighters from Mayadeen, including several leaders.

Syrian regime units backed by Iranian militias and the Russian air force have advanced deep into Deir az-Zour over the past month.

IS have still managed to launch several counter-attacks, killing scores of Syrian fighters and capturing two Russian men - believed to be mercenaries - in at attempt to cut off supply routes for pro-Damascus forces.

IS have been all but defeated in Iraq, where the last pockets of territory are being mopped up by the Iraqi army.

Syrian regime troops have managed to break a siege on government areas of Deir az-Zour, while a US-backed Kurdish led force are planning a final assault on the last districts of Raqqa still under IS control.