Russia has denied interfering with evidence at the site of the suspected Syrian chemical attack, which led to Western air strikes on Saturday.
In an interview for BBC’s Hardtalk, Russian Foreign Minister Sergei Lavrov said: «I can guarantee that Russia has not tampered with the site.»
The US raised concern at the international chemical weapons agency.
International inspectors will be allowed to visit the site on Wednesday, the Russian military has announced.
A nine-strong team from the agency, the OPCW (Organisation for the Prohibition of Chemical Weapons), has been waiting nearby in the Syrian capital Damascus for the green light.
Douma was a rebel stronghold at the time of the attack on 7 April and is now under the control of the Syrian government and Russian military.
UK Prime Minister Theresa May has defended Britain’s involvement in the air strikes, saying it was to prevent «further human suffering», as opposition parties said MPs should have been consulted in advance.
What happened in Douma?
The suspected attack, denied by Syrian President Bashar al-Assad’s government, reportedly killed dozens of people in Douma, in the Eastern Ghouta region.
Two bombs filled with chemicals were reportedly dropped several hours apart on the town.
Syrian medical sources say bodies were found foaming at the mouth, and with discoloured skin and cornea burns.
US sources said they had obtained blood and urine samples from victims which had tested positive for chlorine and a nerve agent.
What did Lavrov say exactly?
Kenneth Ward, US envoy to the OPCW, said: «It is our understanding the Russians may have visited the attack site.
«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.»
Speaking to the BBC, the Russian foreign minister denied chemical weapons had been used in Douma.
«I cannot be impolite with the heads of other states, but you quoted the leaders of France and the UK and US and, frankly speaking, all the evidence they quoted was based on media reports and social media.»
The event did not take place, he said. «What did take place was the staged thing,» he added.
Mr Lavrov also questioned why the US, UK and France had carried out their retaliatory air strikes before OPCW inspectors were able to visit the site.
Russia and the West, he added, were facing a situation worse than during the Cold War due to a lack of channels of communication.
In other developments:
- The US says it is considering fresh economic sanctions against Russia «in the near future»
- EU foreign ministers meeting in Luxembourg said they understood the air strikes had had «the sole objective» of preventing further use of chemical weapons by the Syrian government
What is the situation with the inspectors?
OPCW emergency talks were held in The Hague on Monday.
The UK’s envoy to the OPCW, Peter Wilson, called for the inspectors to be given «unfettered access» to Douma and dismissed as «ludicrous» Russian suggestions that Britain had helped stage a fake attack.
At the end of the day, the Russian embassy held a press conference at which Russian chemical and biological protection troops commander Maj-Gen Igor Kirillov announced that inspectors would visit Douma on Wednesday.
A UN security team would first check the area on Tuesday, the general said. The OPCW itself has not confirmed the plans.
What was targeted on Saturday?
The US says 105 missiles were launched and it believes none were intercepted by Syrian defences. It says Syria’s chemical weapons programme has been set back years.