The Syrian army and its allies recaptured an oilfield from ISIS near the eastern city of Deir Ezzor on Saturday in further advances against the militants.
Government forces also seized a part of a main highway running from Deir Ezzor down to the city of al-Mayadeen, to which many ISIS militants have retreated, the Syrian Observatory for Human Rights monitoring group said.
The British-based monitoring group said that advance would block potential ISIS reinforcements from al-Mayadeen.
The advances put yet more pressure on ISIS’s shrinking caliphate, which once stretched across northern and eastern Syria, and northwestern Iraq.
In Syria, the group holds much of Deir Ezzor province and half the city, as well as a pocket of territory near Hama and Homs.