Russia on Wednesday said it was pushing on with its support for President Bashar al-Assad's forces in Syria, after deflecting blame from Damascus over a suspected chemical attack in Idlib province which killed at least 72 civilians including 20 children.

“Russia and its armed forces are continuing the operation to support the anti-terrorist operation to liberate the country, which the Syrian armed forces are conducting,” Kremlin spokesman Dmitry Peskov told journalists.

Iran condemns 'all use of chemical weapons' in Syria

Iran condemned “all use of chemical weapons” in Syria, but suggested the blame for this week's deadly attack may lie more with “terrorist groups” than President Bashar al-Assad's regime.

“Iran strongly condemns all use of chemical weapons regardless of who is responsible and who are the victims,” said foreign ministry spokesman Bahram Ghassemi.

However, he said it was necessary to avoid “rushed judgements and accusations that benefit... certain actors”.

The White House and other Western countries have blamed Assad for Tuesday's attack in Idlib province which killed at least 72 civilians including 20 children.

But Ghassemi emphasised that “terrorist groups” have been known to transfer, store and use chemical weapons in Syria.

“Ignoring the need for the chemical disarmament of armed terrorist groups has harmed the process of chemically disarming Syria (as a whole) and the Islamic republic of Iran has raised its concerns about this on several occasions,” he said.

Iran and Russia have been Assad's key backers in the six-year conflict, and refer to all rebel groups in the country as “terrorists”.

Moscow said Wednesday that the deaths in Idlib were caused when a Syrian jets bombed a rebel depot containing “toxic substances”.