Beirut (AFP) - Islamic State group jihadists have retaken nearly half of Albu Kamal in eastern Syria in a counter-attack on what had been the last significant town under their full control, a monitor said Friday.
"IS started counter-attacking on Thursday night and retook more than 40 percent of the town of Albu Kamal," Rami Abdel Rahman, head of the Britain-based Syrian Observatory for Human Rights, told AFP.
Syrian regime forces and allied fighters had recaptured the town, which lies on the border with Iraq in the eastern Deir Ezzor province, from the jihadists on Thursday.
Albu Kamal lies at the heart of what used to be the sprawling "caliphate" the group declared in 2014 over swathes of Iraq and Syria.
"The jihadists went back in and retook several neighbourhoods in the north, northeast and northwest," Abdel Rahman said. "IS is trying to defend its last bastion."
The jihadist organisation has in the space of a few weeks seen its caliphate shrink to a small rump and lost major cities such as Mosul, Raqa and Deir Ezzor.
Albu Kamal was the last town of note it controlled and losing it would cap the group's reversion to an underground guerrilla organisation with no urban base.
According to Syria state TV, regime and auxiliary forces had retake full control of it by Thursday.
The Observatory said most of the fighting was done by the Lebanese Shiite group Hezbollah and elite forces from its backer Tehran, as well as militia groups from Iraq.