Syrian fighters backed by the United States have seized the town of Hajin in eastern Syria, the Syrian Observatory for Human Rights war monitoring group and a source in the militia leading the battle said on Friday.
Hajin is the last big town held by Islamic State in its remaining pocket of territory east of the Euphrates River near the border with Iraq. The US-backed Syrian Democratic Forces (SDF), spearheaded by the Kurdish YPG militia, have been battling to eradicate Islamic State for several months in the area.
A YPG source said the SDF was now in control of Hajin, where some small remaining pockets of Islamic State resistance would be finished off in the next day or two.
The capture of Hajin leaves Islamic State in control of a diminishing strip of territory along the eastern bank of the Euphrates River in the area where the US-backed operations are focused.
The jihadists also control some desert terrain west of the river in territory otherwise controlled by the Damascus government and its allies.
SDF commander-in-chief Mazloum Kobani told Reuters on Thursday that at least 5,000 Islamic State fighters remain holed up in the pocket of territory including Hajin and that they had decided to fight to the death.
This includes some 2,000 foreign fighters, mostly Arabs and Europeans along with their families.
Kobani also said it was possible that Islamic State leader Abu Bakr al-Baghdadi was in eastern Syria, but the SDF could not be sure because he often disappears.
Islamic State was driven from nearly all the territory it once held in Syria last year in separate campaigns waged by the US-backed SDF on the one hand, and the Russian-backed Syrian government on the other.