Syria attack 'calls into question' peace process: Opposition

Beirut: A suspected chemical attack that killed dozens in a northwestern Syrian town on Tuesday "calls the political process into question", the opposition's chief negotiator at peace talks said.

"If the United Nations cannot deter the regime from carrying out such crimes, how can it achieve a process that leads to political transition in Syria?" asked Mohamad Sabra.

Sabra is the head negotiator for the main opposition High Negotiations Committee (HNC) that took part in recent peace talks hosted by the United Nations in Geneva.

"This crime... Will force us to re-evaluate whether it's feasible to take part in a political process sponsored by the UN if it is unable to enforce its own resolutions, notably UNSCR 2118," Sabra said.

UN Security Council Resolution 2118 was passed after a massive chemical weapons attack that killed hundreds in several opposition areas around Damascus in 2013.

Today, at least 58 people including 11 children died after air strikes on the rebel-held town of Khan Sheikhun, the Syrian Observatory for Human Rights said.

The Britain-based monitor said the warplanes released "toxic gas" in the town but could not confirm the nature of the material.

The attack came as the European Union and UN hosted a conference in Brussels on Syria's future, with EU diplomatic chief Federica Mogherini saying the regime in Damascus bears "primary responsibility" for the attack.