Image: File photo, smoke rises over Saif Al Dawla district, in Aleppo, Syria (AP Photo/ Manu Brabo, File).

A chlorine attack has killed six people, including an entire family, and poisoned a further 70 in northwest Syria.

Syrian doctors report that witnesses saw helicopters dropping barrels which released a suffocating gas on impact with the ground on the rebel-controlled town of Sarmin, Idlib.

“Attacking a village and its civilian population with chlorine shows once again that the Syrian conflict knows no limits”, said Jane-Ann McKenna, Director of MSF Ireland. Medecins Sans Frontiéres supports the hospital in the town in which wounded were treated.

“We saw people arriving at the hospital from a neighbouring village”, said Dr T, the director of Sarmin hospital.

“Amongst them, there was a family of three young children with their parents. They were in a very serious condition, dying. Their parents were able to speak but they were having a lot of difficulty breathing.”

MSF reports that the family died in the hospital. The grandmother of the children died of asphyxiation before reaching medical assistance.

MSF say: “The events and symptoms described by the medical staff of the hospital leave no doubt as to the presence of chlorine poisoning. There were no symptoms consistent with any other toxic products.

“It was dark so we couldn’t see any particular colour in the sky”, stated the hospital director.

“But the air smelt of cleaning products and their clothes had the distinctive smell of chlorine.”

Earlier this month the UN Security Council adopted a resolution threatening measures if chemical attacks were made in Syria.

“There were 20 patients in serious condition, agitated, foaming blood at the mouth and showing skin rashes,” said another hospital doctor.

The hospital team treated 70 victims from two towns, and a group of volunteer first aid workers from the Syrian Civil Defence who were affected by the gas when they arrived to give assistance.