Claim adds to growing concerns that Assad's government is still using chemical weapons after hundreds killed in attack last year

This article is more than 6 years old

This article is more than 6 years old

A leading human rights group says it has strong evidence that Syria's army used chemical weapons on rebel-held areas last month.

Human Rights Watch said on Tuesday that forces loyal to President Bashar al-Assad likely used chlorine gas on three towns in northern Syria in mid-April.

The New-York based group said chlorine canisters appear to have been embedded into crude explosive-laden barrels and dropped on rebel-held areas by military helicopters, according to interviews with witnesses, video footage and photographs.

The claim adds to growing concerns that Syria's government is still using chemical weapons, months after a chemical attack killed hundreds of civilians last August.

In late April, the UN's chemical watchdog said it would investigate the chlorine claims.