Amnesty International has condemned the Syrian government’s alleged recent chlorine attack in northern Syria on Tuesday.

In a statement published on its website titled “Syria: Evidence of a fresh war crime as chlorine gas attack kills entire family,” Amnesty said that a family of six people, including three young children, was killed late on Monday in a chlorine gas attack when regime forces dropped four barrel bombs on Sermin and Qminas villages in Idlib province.

“These horrific attacks that resulted in civilians, including small children, suffering excruciating deaths, are yet more evidence that the Syrian government forces are committing war crimes with impunity,” said Philip Luther, Amnesty’s director of Middle East and North Africa’s programme.

“The situation in Syria must be referred to the International Criminal Court as a matter of urgency,” he added.

The statement follows a report by the organisation released on Tuesday on findings into the deaths of 115 civilians, including 14 children, in government aerial attacks on Raqqa – a stronghold of the Islamic State (IS) militant group in Syria – which took place between 11 and 29 of November 2014.

Moreover, the organisation made reference to a fact-finding mission of the international Organisation for the Prohibition of Chemical Weapons, which found “compelling confirmation” of constant use of chemical weapons in 2014.

The Syrian opposition has repeatedly accused President Bashar al-Assad’s government of using chemical and toxic weapons against civilians since August 2013, when such an attack reportedly killed between 300 and 1,400 civilians in the Damascus suburb of Ghouta.

However, Syrian government officials have denied the allegations, charging that the gas attacks were carried out by rebel forces.