The Syrian Democratic Forces (SDF) made fresh gains against the "Islamic State of Iraq and Syria" (ISIS) in the group's eastern Syria stronghold Monday (December 24th), forcing hundreds of people to flee the fighting, AFP reported.

The SDF, with aerial support from the international coalition, closed in on the two main spots where ISIS has been holding out, the Syrian Observatory for Human Rights said.

"There is currently fighting around the villages of al-Shaafa and al-Sousa," said Observatory head Rami Abdel Rahman.

The two villages are the main hubs in what is left of ISIS’s last pocket in the Euphrates River valley, near the Iraqi border. If ISIS loses the villages, it will no longer control any populated areas in Iraq or Syria.

"The latest developments are in favour of the SDF and it appears ISIS may collapse soon," Abdel Rahman said.

The Arab-Kurd alliance was able to repulse several ISIS attacks and was advancing from three different directions, said SDF spokesman Kino Gabriel.

A few hundred holdout fighters are defending the last rump of the group’s self-proclaimed "caliphate".

The SDF on Sunday said it had evacuated 1,000 civilians from the area where the fighting was taking place.