Daesh militants have gained some ground in Damascus after driving out Bashar al-Assad's army units from al-Qadam, a district that the opposition abandoned last week, a war monitor said.

In fighting that lasted 24 hours, the terrorist group killed 36 Syrian soldiers, the British-based Syrian Observatory for Human Rights said. The regime forces could not immediately be reached for comment.

The district of al-Qadam lies in the Syrian capital's southern suburbs and has not been part of the month-long offensive waged by the army against the opposition in Eastern Ghouta. It is located next to the Yarmouk Palestinian refugee camp, a scene of fierce fighting early in the seven-year conflict. Last week, the group that had held part of al-Qadam for years quit the district for opposition areas in northern Syria under an evacuation deal with the regime, allowing the army to move in.

However, Daesh fighters that had held a separate part of the district, and had sporadically fought the opposition there, launched an assault to take the area they had vacated. Daesh has lost almost all its territory in Syria. It now controls only the small pocket in Qadam, a patch of territory in southwest Syria near the borders with Jordan and Israel, and two small areas of the desert on each side of the Euphrates near the border with Iraq.