Assad will be judged as a war criminal, says France

French Foreign Minister Jean-Marc Ayrault on Thursday said that "a day will come when international justice will give its verdict on Bashar al-Assad who is massacring his people."

Speaking to news channel CNEWS, he added: "These crimes must not go unpunished. In any case, there are investigations, United Nations commissions... there will be a war crimes trial."

At least 86 people were killed on Tuesday in rebel-held Khan Sheikhun in northern Syria in a suspected chemical attack that left people choking and foaming at the mouth.

France is again pushing for a resolution at the United Nations to condemn the attack blamed by the West on Assad's regime, but Ayrault did not sound optimistic after the first discussions yesterday at the international body.

"It's difficult because up to now every time we have presented a resolution, there has been a veto by Russia and sometimes by China ... but we must cooperate because we need to stop this massacre," he added.

Moscow, which launched a military intervention in 2015 in support of Assad's forces, has defended the Syrian government against accusations it is responsible for the attack.

Survivors of the deadly chemical attack say they were gassed as they slept, a media report said.

They also described that the gas bombs were dropped from planes, directly contradicting the government's version of events. Abdul Hamid Youssef said that the attack shook him from a deep sleep. He awoke, finding it difficult to breathe. Leaping from bed, Youssef scrambled to make sure his nine-month-old twins were still alive. Apparently unharmed, he passed them to his wife and told her to stay in the house.

Rushing outside to check on his parents next door, Youssef passed people staggering and falling in the street, the news report said.

Youssef and many members of his extended family live on the northern edge of Khan Sheikhoun, a town in Idlib province, where the attack took place. On Tuesday, airstrikes battered an area near their local bakery, meters from Youssef's home.

Assad has been accused of using chemical weapons in the strikes. It was meant to rattle the rebel-held area. Instead it killed many and injured more than 200. Youssef arrived in his parents' house to find his two brothers dead. Panicked, he rushed back to his home to check on his wife and babies.

"There was foam coming out of their mouths, there were convulsions. They had all been on the floor," Youssef told said on Wednesday, sobbing.

"My kids, Ahmad and Aya, and my wife… they were all martyred. My entire family's gone." Global condemnation intensified on Wednesday, the day after the attack, one of the deadliest since the Syrian war began six years ago.

At the UN, Western powers lambasted Russia for standing by the regime.