86 dead in suspected Syria chemical attack: new toll

"There were also 20 women among the dead and the death toll could rise further because there are people missing," the Syrian Observatory for Human Rights said.

The UN Security Council met Wednesday to debate a Western-drafted resolution condemning the air strike.

But Moscow, which holds a veto, defended its Damascus ally saying that while Syrian aircraft had carried out a strike, the chemicals were part of a "terrorist" stockpile of "toxic substances" that had been hit on the ground.

Rebel groups led by former Al-Qaeda affiliate Fateh al-Sham Front vowed revenge for Tuesday's strike in the town of Khan Sheikhun in Idlib province in the northwest.