The Syrian government and the United Nations chemical weapons investigation envoy to Syria have agreed on the terms under which the UN is allowed access to the site of an alleged chemical weapons attack that killed hundreds on Wednesday in Damascus.
The announcement of the agreement late on Sunday included an assurance to the UN by the Syrian government that it would also observe a ceasfire during the probe in al-Ghouta, to begin on Monday.
The agreement "is effective immediately and it will allow the UN delegation to investigate allegations of using chemical weapons on August 21 in Damascus suburbs," state TV reported.
Reaction to the Syrian goverment's decision, five days after the incident, was greeted with a host of reactions by the United States, France, Britain and Russia.
A senior White House official told Al Jazeera, that this move "is too late to be credible" and that the evidence would now be "corrupted", and that there was "very little doubt" that Syrian forces had used chemical weapons in al-Ghouta.
“We have seen the reports that after five days of refusing to allow the UN investigative team immediate and unimpeded access to the site of a reported August 21 chemical weapons attacks, the regime may allow access tomorrow.
"If the Syrian government had nothing to hide and wanted to prove to the world that it had not used chemical weapons in this incident, it would have ceased its attacks on the area and granted immediate access to the UN – five days ago.
"At this juncture, the belated decision by the regime to grant access to the UN team is too late to be credible, including because the evidence available has been significantly corrupted as a result of the regime’s persistent shelling and other intentional actions over the last five days.
"Based on the reported number of victims, reported symptoms of those who were killed or injured, witness accounts, and other facts gathered by open sources, the US intelligence community, and international partners, there is very little doubt at this point that a chemical weapon was used by the Syrian regime against civilians in this incident.
"We are continuing to assess the facts so the president can make an informed decision about how to respond to this indiscriminate use of chemical weapons.”
France mirrored US sentiment, with French Foreign Minister Laurent Fabius saying that there was "no doubt" that the Syrian government was to blame for Wednesday's attack.
"The indications are totally convergent on the scale of the massacre and the overwhelming responsibility of the regime... As far as we are concerned, there is no doubt concerning the substance of the facts and their origin," Fabius told a news conference in Jerusalem.
Asked about the Syrian government's decision on Sunday to grant UN inspectors permission to inspect the sites of the suspected chemical strikes, Fabius replied that "this request was already made several days ago".
"The site has been bombed since," he said. "We will see what the actual work that will be done is," he added.
Britain's Foreign Secretary William Hague, also said late on Sunday that evidence of the alleged chemical attack on Wednesday may already be destroyed.
"The fact is that much of the evidence could have been destroyed by that artillery bombardment," he said during a press conference after Damascus gave its green light to the mission by UN inspectors.
"Other evidence could have degraded over the last few days and other evidence could have been tampered with," he said.
Hague expressed concern that too much time had elapsed for the UN inspectors to gather enough concrete evidence.
"We have to be realistic now about what the UN team can achieve," he said.
However, he repeated his belief that Syrian President Bashar al-Assad's forces were responsible for the alleged attack, claiming "there is a lot of evidence already and it all points in one direction".
With the drums of a wider war beating, Syria's ally Moscow bluntly warned the West that military action against Assad's regime would be a "tragic mistake".
"The current fuss around the events of August, 21 is clearly aimed at disturbing the work of independent UN experts on chemical weapons," foreign ministry spokesman Alexander Lukashevich said in a statement.
"It looks especially strange if you remember for how long Paris and London were blocking the deployment of UN inspectors to probe a chemical weapons attack in Khan al-Asal near Aleppo on March 19. We cannot allow the truth about the incident to be blurred. On August 24 we sent a file to the UN in which facts of using chemical weapons by the opposition are documented."
Reuters news agency reported that a statement by Lukashevich said: "We strongly urge those who, by attempting to impose their own results on the UN experts, are raising the possibility of a military operation in Syria to use their common sense and refrain from committing a tragic mistake."