OTTAWA -- Foreign Affairs Minister Chrystia Freeland says the facts behind the Syrian chemical weapons attack must be clearly established so those responsible can be held accountable.

Freeland stopped short of blaming President Bashar Assad's government but she says it will be a "damning indictment" of him if that turns out to be the case.

She says Canada and the U.S. are the two leading funders of the United Nations organization that investigates the use of the chemical weapons, which will play a role in establishing the facts of Tuesday's chemical attacks in Syria.

Nikki Haley, the U.S. ambassador to the UN, says the attacks have "all the hallmarks" of Assad's government and the U.S. may take action if the UN Security Council fails to act.

Freeland urged all permanent members of the Security Council to support a resolution by the U.S., Britain and France condemning the use of chemical weapons and threatening consequences.

The UN envoy for Russia, which backs Assad, opposes the resolution, saying it is based on information from "discredited" groups.