Russian president Vladimir Putin has described US claims that the Syrian government is responsible for the alleged chemical weapons attacks on civilians in Damascus as "utter nonsense."
Speaking to journalists in Vladivostok, Putin said that Syrian president Bashar al-Assad had no motive to launch the attacks because his forces were winning the war.
"That is why I am convinced that [the chemical attack] is nothing more than a provocation by those who want to drag other countries into the Syrian conflict, and who want to win the support of powerful members of the international arena, especially the United States," he said.
He called on the US to present evidence of Assad's guilt to the security council of the UN, and called its failure to do so "simply disrespectful".
"If there is evidence it should be shown. If it is not shown, then there isn't any," he said.
Putin also expressed surprise at the decision by the British parliament to veto UK involvement in military strikes.
"I will be honest: this was completely unexpected for me," he said.
"This shows that in Great Britain, even if it is the USA's main geopolitical ally in the world... there are people who are guided by national interests and common sense, and value their sovereignty."
Russia, a key strategic ally of Syria, has previously vetoed two UN draft resolutions on Syria, and warned that "any unilateral military action bypassing the UN Security Council" would be a "direct violation of international law".
Putin called on Obama to live up to his title as Nobel Peace Prize laureate and consider the civilian deaths military strikes would cause. He added that next week's G20 summit in St Petersburg presented the ideal opportunity for nations to discuss the conflict.
The US is believed to be gearing up for strikes against Syrian targets as early as Sunday evening.
UN weapons inspectors left Syria today ahead of schedule, crossing the border into Lebanon, fuelling speculation that air strikes are imminent.
The 20-strong team has taken blood and tissue samples from victims of the strike during its three visits to the eastern area of Ghouta in Damascus, as well as samples of soil and clothing.
These will be sent to laboratories in Europe, where tests for gases such as the nerve agent sarin and poisonous mustard gas will be conducted. The results are expected in about two weeks.
On Friday, US secretary of state John Kerry briefed the foreign ministers of key European and Gulf allies, as well as the head of the Arab League on US plans, a senior state department official said.
In a survey on Saturday, it was revealed that 64% of the French public oppose military involvement in the conflict.
Kerry has heaped praise on the country for pledging to support the US in military operations against Syria, describing the French as the United States' "oldest ally".
Neither the French nor the US governments require the approval of parliament to launch military attacks.