London: British Foreign Secretary William Hague on Sunday said that any evidence of a chemical attack by the Syrian regime may have already been 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 a mission by UN inspectors.
"Other evidence could have degraded over the last few days and other evidence could have been tampered with," he said.
UN experts are tomorrow to start investigating the site of the alleged attack as a sceptical Washington said Syria`s acceptance had come too late.
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".
More than 100,000 people have been killed in Syria since an uprising against Assad`s rule flared in March 2011, the UN says.