In eastern Ghouta, rescue workers were still retrieving bodies on Tuesday from the basement of a school that was bombed by government or Russian jets on Monday, a spokesman for the Syrian Civil Defence group said.
A USA military official told CNN that Russian private military contractors remain in the area and are using local pro-regime troops to scout coalition positions.
Rami Abdel Rahman, head the Britain-based Observatory said, "Three missiles from a single air strike hit the school, where the underground level was being used as a shelter".
The UN refugee agency also urgently called on Tuesday for the protection of those who have fled and for the hundreds of thousands of civilians still trapped by fighting who are in "dire need of aid".
He added that despite constant attempts of the militants to derail the peaceful initiatives in Eastern Ghouta, the Russian side is in permanent talks with leaders of the militant groups aiming at stopping the military actions and avert a humanitarian disaster.
ISIS has lost nearly all its territory in Syria after two rival offensives a year ago by the Syrian forces, backed by Russian Federation and Iran, and an alliance of Kurdish and Arab militias backed by the United States.
Addressing ruling party legislators in Ankara, Erdogan said: "On the one hand you say you're our strategic partner, and then you go collaborate with terrorists".
It was the latest town to be captured by the Syrian troops and allied militia in a swift advance over the last few days.
The Observatory said that along with the 36 troops killed, dozens more were wounded or captured in the clashes with IS militants in Qadam.
The clashes come after ISIS militants drove out pro-government forces from parts of the neighborhood that rebels abandoned last week as part of an evacuation deal with the Syrian government. It says the Syrian government has sent reinforcements into the area.
In a series of videos posted on the Syrian presidency's Twitter account, Assad is seen getting behind the wheel of a Honda Civic, unguarded by the usual army of bodyguards, and taking to the road to Ghouta, "to see the situation".
Syrians pack their belongings as they flee their home in the town of Utaya in the Syrian rebel enclave of Eastern Ghouta on 1 March 2018.