Around 100 Syrians have been hospitalised with breathing difficulties in Aleppo, state media and a monitor said Sunday, after allegations rebels fired "toxic gas" on the regime-held city the previous day.

A rebel alliance in nearby Idlib denied any involvement in the alleged attack. State news agency SANA reported "107 cases of breathing difficulties" in an updated toll on Sunday. The Syrian Observatory for Human Rights, a Britain-based monitor, said a total of 94 people were hospitalised, but most had been discharged and the 31 cases that remained were not critical.