Foreign-backed militant groups have launched a chemical attack against a neighborhood in the northern Syrian city of Aleppo, injuring scores of people.

The attack hit al-Khalidiya neighborhood in the government-held city on Saturday, foreign news agencies and state television reported, saying close to 50 people have been hospitalized.

Doctors said most of those admitted to hospitals have breathing problems and blurred vision. State TV showed footage of medical professionals treating men and women on hospital beds.

There was a stench of gas in Aleppo city after projectiles were fired, head of the so-called Syrian Observatory for Human Rights Rami Abdurrahman. Health official Haj Taha said symptoms suggested that the poisonous gas used was chlorine.