Assad denies he has used chemical weapons, and the Trump administration has yet to present hard evidence of what it says precipitated the allied missiles attack: a chlorine gas attack on civilians in Douma on April 7.
And Russian foreign minister Sergey Lavrov said relations between Moscow and the West were worse than at the time of the Cold War.
Diplomatic tensions between the United Kingdom and Russian Federation deepened amid claims that Moscow was blocking investigators from reaching the site of a chemical weapons attack in Syria.
"It is our understanding the Russians may have visited the attack site", US Ambassador Kenneth Ward said at a meeting of the OPCW in The Hague on Monday.
Mr Uzumcu was speaking as the start of OPCW emergency talks in The Hague.
Moscow blamed the delay on the Western air strikes.
The UK's representative at the OPCW, Peter Wilson, said: "It is imperative that the Syrian Arab Republic and the Russian Federation offer the OPCW fact finding mission team their full co-operation and assistance to carry out their hard task".
USA sources said they had obtained blood and urine samples from victims which had tested positive for chlorine and a nerve agent.
What else did Mr Lavrov say?
Mr Lavrov said the "deconfliction channel" to prevent a clash between USA and Russian forces had done its job and a confrontation had not been close.
"We are concerned they may have tampered with it with the intent of thwarting the efforts of the OPCW Fact- Finding Mission to conduct an effective investigation".
"I can not be impolite to the heads of other states ... but frankly speaking, all the evidence they quoted was based on media reports and social networks". "What did take place was the staged thing", he added.
The OPCW inspectors will not assign blame for attacks.
"We were not looking for war".
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What is the situation with the inspectors?
Inspectors have not yet been granted access to sites in Douma, the British delegation to the OPCW said Monday, citing the agency's director general.
The team was still not been granted safe passage on Monday, CNN quoted British envoy to the OPCW, Peter Wilson, as saying.
What was targeted on Saturday?
Meanwhile, media reports noted that the United Kingdom government has confirmed a "20-fold" increase in disinformation being spread by Kremlin-linked social media "bot" accounts since the United Kingdom, US and France attacked Syria's chemical weapons infrastructure on Saturday.
Trump tweeted "Mission Accomplished" on Saturday after U.S., French and British warplanes and ships launched more than 100 missiles almost unopposed by Syrian air defenses.
The Prime Minister will tell MPs that the strikes were in the national interest because the use of chemical weapons can not be normalised, including in the UK.
The other two were suspected chemical weapons facilities at Him Shinshar near Homs.
But shadow attorney general Baroness Chakrabarti questioned the Government's justification for the airstrikes, telling BBC Radio 4's Today programme: "You can't use force under worldwide law just to punish Syria for bad behaviour".
The US has some 2,000 troops in eastern Syria, mainly supporting the fight against the Islamic State group.
White House press secretary Sarah Huckabee Sanders said in a statement Monday: "We are considering additional sanctions on Russian Federation and a decision will be made in the near future". In a statement, she said "he wants USA forces to come home as quickly as possible".
The US has stressed continuing US troop involvement in Syria and outlined plans for new economic sanctions against Russian Federation for enabling the government of Bashar Assad. "France has the same position".
"It was retaliation, not an act of war", Macron said in justifying the operation a day before the French parliament was set to debate it.