UN Secretary-General Antonio Guterres on Wednesday said a suspected chemical weapons attack in a rebel-held town in Idlib Province shows war crimes continue in Syria, reported AFP news agency.

"The horrific events of yesterday demonstrate unfortunately that war crimes are going on in Syria (and that) international humanitarian law is being violated frequently," said Guterres as he went into a Syria aid conference in Brussels.

At least 72 people, including 20 children, were killed in the alleged chemical weapons attack, according to the Syrian Observatory for Human Rights. 

The US, Britain and France blamed the Syrian government for the attack. Both the Syrian military and ally Russia have denied the use of chemical weapons.

Earlier, Staffan de Mistura, the UN Special Envoy for Syria, also condemned the attack, describing it as “horrific.”

The UN Security Council will convene for an open emergency meeting on Wednesday to discuss reports on the attack.