THE Russian military has claimed an alleged chemical attack in Syria was staged and directed by Britain.

Volunteer first responders and activists said a chemical attack by the Syrian government killed more than 40 people in the town of Douma, which drew international outrage and prompted Washington and its allies to consider a military response.

Moscow warned against any strikes and threatened to retaliate.

Russian Defence Ministry spokesman Major General Igor Konashenkov released statements by medics from Douma's hospital who said a group of people toting video cameras entered the hospital, shouting that its patients had been struck with chemical weapons and causing panic.

The medics said none of the patients were hurt by chemicals.

Maj Gen Konashenkov said Britain was "directly involved in the provocation".

Russia's foreign minister Sergey Lavrov said earlier that Russian experts had inspected the site of the claimed attack and found no trace of chemical weapons.

As fears of a Russia-West military confrontation mounted, French President Emmanuel Macron expressed his "deep concerns" over the situation in Syria in a phone call with Russian President Vladimir Putin.

According to a statement by the French presidency, Macron called for dialogue between France and Russia to "continue and intensify" to bring peace and stability to Syria.

The Kremlin said Putin warned against rushing to blame the Syrian government before conducting a "thorough and objective probe".

The Russian leader warned against "ill-considered and dangerous actions ... that would have consequences beyond conjecture".

Putin and Macron instructed their foreign and defence ministers to maintain close contact to "de-escalate the situation", the Kremlin said.

US President Donald Trump emerged from a meeting with his national security team on Thursday without a "final decision" on how to respond to the suspected chemical attack.

White House spokeswoman Sarah Huckabee Sanders said Mr Trump held a meeting with his team to discuss the situation, but "no final decision has been made".

She said US officials are "continuing to assess intelligence" and are "engaged in conversations with our partners and allies".