Russia's foreign minister claimed on Friday that a suspected chemical attack in the Syrian town of Douma last weekend was staged with the help of an unspecified foreign intelligence agency.

A day before a team from the international chemical weapons watchdog was due to arrive in Douma, just east of Damascus, Sergey Lavrov said Russian experts have already inspected the site of the alleged attack and found no trace of chemical weapons.

During a press briefing on Friday, Mr Lavrov said he had "irrefutable evidence" that the attack was staged as part of a "Russophobic campaign" led by one country, which he did not name.

Moscow, he said, has "irrefutable information that it was another fabrication." Lavrov did not offer evidence to back up his claim. Other Russian officials — both from Moscow and speaking at the United Nations — alleged quickly after Saturday's suspected attack that the images of the victims in Douma were a sham.

The Russian Foreign Ministry also claimed that following Syrian rebels' withdrawal from the eastern Ghouta suburbs of Damascus, stockpiles of chemical agents were allegedly found there. The ministry also pointed at previous use of chemicals by the rebels in fighting with Syrian government troops.

Speaking to reporters in Moscow, Lavrov reiterated a strong warning to the West against military action in Syria, saying any such "adventures" in Syria would increase flows of refugees into Europe.

"I hope no one would dare to launch such an adventure now," Lavrov said.

Russia has been a staunch ally of Syrian President Bashar Assad's government and has helped turn the tide of war in his favour since entering the conflict in September 2015. Syria's civil war, which began as a popular uprising against Assad, is now in its eighth year.

A fact-finding mission from the Organization for the Prohibition of Chemical Weapons is expected to head to Douma, the site of the suspected attack. Both the Russian military and the Syrian government said they would facilitate the mission and ensure the inspectors' security.

Lavrov said Russia expects OPCW team to quickly visit the site. The Russian military said its chemical experts visited Douma shortly after the alleged attack and found no trace of chemical agents in ground samples. It also said Russian officers found no patients with chemical attack symptoms at a local hospital, and no indication of any burials having taken place of the victims.

On Thursday, Russia's military said Douma has been brought under full control of the Syrian government under a Russia-mediated deal that secured the evacuation of the rebels and thousands of civilians after it was recaptured by Syrian forces. The government, however, said evacuations from Douma were ongoing and no Syrian government forces had entered the town.

Douma and the sprawling eastern Ghouta region near the capital, Damascus, had been under rebel control since 2012 and was a thorn in the side of Assad's government, threatening his seat of power with missiles and potential advances for years. The government's capture of Douma, the last town held by the rebels in eastern Ghouta, marked a major victory for Assad.

The suspected poison gas attack in Douma, which killed more than 40 people, has drawn international outrage and prompted the United States and its allies to consider a military strike on Syria, something Moscow has strongly warned against.

Lavrov said that "intelligence agencies of a state that is now striving to spearhead a Russo-phobic campaign were involved in that fabrication." He didn't elaborate or name the state.

In a reference to the U.S., he said that it "it would only benefit those who are protected by the ocean and expect to sit there and engage in continuous efforts to stir up the region in order to advance their geopolitical goals."

Russia has dismissed the purported chemical attack as fake and strongly warned the U.S. and its allies against launching a military strike in Syria.

Lavrov noted that Russian and U.S. militaries have a hotline to prevent incidents, adding that it's not clear if it would be sufficient amid mounting tensions.

"We are open for those contacts, they help to understand each other better," Lavrov said.

Syria Russia Donald Trump Vladimir Putin