International inspectors are pushing to visit the site of a suspected gas attack which brought US-led missile strikes on Syria and heightened the diplomatic confrontation between the West and Russia.
- The US has told the global watchdog that Russia may have tampered with the site
- Russia's Foreign Minister has denied the allegations
- The UK says inspectors have not been granted access to the sites yet
Russian President Vladimir Putin said on Sunday more Western attacks on Syria would bring chaos to world affairs, and Washington prepared to increase pressure on Russia with new economic sanctions.
Moscow also condemned the Western countries for refusing to wait for the findings of the Organisation for the Prohibition of Chemical Weapons (OPCW) inspection team on the alleged attack before launching the strikes.
But the US envoy to the global watchdog said on Monday that Russia may have tampered with the site of the incident on April 7 in Douma outside of Damascus.
"It is long overdue that this council condemns the Syrian Government for its reign of chemical terror and demands international accountability those responsible for these heinous acts," US ambassador Kenneth Ward said in comments seen by Reuters.
Russian Foreign Minister Sergei Lavrov denied the allegations in an interview with the BBC.
"I can guarantee that Russia has not tampered with the site," Mr Lavrov said.
Inspectors for the Hague-based OPCW met Syrian Deputy Foreign Minister Faisal Mekdad in the presence of Russian officers and a senior Syrian security official in Damascus for about three hours on Sunday.
The inspectors were due to attempt to visit Douma, but the British delegation to the OPCW said they had not yet been granted access, citing the agency's director general.
Douma, which lies in the eastern Goutha district on the outskirts of the capital, was one of the last bastions near Damascus of rebels fighting to topple Syrian President Bashar al-Assad, and the alleged attack took place amid a ferocious government offensive.
The United States, France and Britain launched 105 missiles targeting what the Pentagon said were three chemical weapons facilities in Syria in retaliation for the suspected poison gas attack in Douma on April 7.
The Western countries blame Mr Assad for the Douma attack, which a Syrian medical relief group said killed dozens of people and thrust Syria's seven-year-old conflict into the forefront of global concern once again.
The Syrian Government and its Russian ally deny involvement.
May to face questions over Syria strikes
In the aftermath of the alleged chemical attack, the remnants of the rebel army evacuated, handing Mr Assad one of the biggest victories in a war that has killed about half a million people and laid waste to whole cities.
The US-led strikes did nothing to alter the strategic balance or dent Mr Assad's supremacy and the Western allies have said the aim was to prevent the further use of chemical weapons, not to intervene in the civil war or topple Mr Assad.
In London, British Prime Minister Theresa May is facing criticism over her decision to bypass parliament and take part in the air strikes.
Ms May will make a statement to parliament on her decision and will repeat her assertion that Mr Assad's forces were highly likely responsible for the attack.
The allies could not wait "to alleviate further humanitarian suffering caused by chemical weapons attacks", according to excerpts of her speech.
But she will be questioned over why she broke with a convention to seek parliamentary approval for the action, a decision that she and her ministers say was driven by the need to act quickly.
Jeremy Corbyn, leader of the main opposition Labour Party, has questioned the legal basis for Britain's involvement.
Britain has said there are no plans for future strikes against Syria, but Foreign Secretary Boris Johnson warned Mr Assad that all options would be considered if chemical weapons were used against Syrians again.