Vladimir Putin has claimed fake chemical weapons attacks in Damascus are being planned as a possible justification for further US airstrikes in Syria.
The Russian president said Moscow had intelligence that "provocations" would be carried out with the sole purpose of pinning the blame on Bashar al Assad's regime.
Russia has rejected suggestions from the outset that the Syrian government was behind a gas attack in Idlib province which killed more than 80 people, including many children.
But a White House official accused Moscow of orchestrating a campaign of misinformation to deflect blame away from the Assad regime and "confuse the world."
The US retaliated with airstrikes on a Syrian airbase from which it believes the chemical attack in the rebel-held town of Khan Sheikhoun was launched. Both the Syrian regime and Russia have denied they were involved.
Mr Putin told a TV news conference: "We have information from various sources that such provocations - I cannot call them otherwise - are being prepared in other regions of Syria, including in the southern outskirts of Damascus, where they are again planning to throw some kind of substance and accuse Syrian official authorities of using it."
He appealed to the United Nations to launch an official investigation into the attack, comparing allegations targeting Mr Assad to US claims that Iraq had weapons of mass destruction before invading the country in 2003.
Britain, France and the US presented a new draft resolution to the UN Security Council also demanding an investigation into the chemical weapons attack.
The new measure would require "full cooperation with the investigation", said the British ambassador to the UN, Matthew Rycroft.
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Mr Putin's comments came as Turkey confirmed sarin gas was used in the attack in northern Syria, and US secretary of state Rex Tillerson arrived in Moscow for crucial talks on Syria.
In the first official trip to Russia by a member of Donald Trump's Cabinet, Mr Tillerson is due to meet with his counterpart Sergei Lavrov, and possibly with Mr Putin.
The top US diplomat carries an ultimatum for his host: either side with world powers in seeking an end to the Syrian war, or continue the alliance with Iran and the militant group Hezbollah in supporting the Assad regime.
Earlier in the day, G7 foreign ministers earlier rejected British Foreign Secretary Boris Johnson's calls to broaden sanctions against Russia and Syria.
The question of added sanctions was barely mentioned in the meetings, according to French foreign minister Jean-Marc Ayrault.
Italian foreign minister Angelino Alfano said Russia must not be "pushed into a corner" over Syria.
Instead of sanctions those meeting agreed there could be no Syrian peace deal with Mr Assad in power.
Mr Tillerson said: "It is clear to us the reign of the Assad family is coming to an end."
However, it was unclear how the group of seven nations expects Mr Assad's departure to be brought about.
Sky's Foreign Affairs Editor Sam Kiley, in Moscow, said: "At the moment Russia holds all the cards when it comes to the future of the Assad regime.
"It is very much in Russia's gift - alongside Iran of course, which is a very significant player - to put pressure on the Assad regime to participate in a transition out of power if it so chooses to go down that route.
"Given that they are militarily very much with the upper hand on the ground in Syria against the Syrian rebels, I don't think they're minded to take that route at all in Moscow, not least at a time when they are, from their perspective, being lectured by the international community on what should go on in Syria.
"I think that the message they will want to deliver is 'we want some respect in this context'."