Syria 's main opposition group has demanded a full international investigation into an alleged chemical weapons attack in the country's north.
The Syrian National Coalition has also asked for an international delegation to be sent to the site of the missile attack in the village of Khan al-Assal in Aleppo province.
The call by the coalition comes a day after Syria’s government and rebels traded accusations about the attack. If it is confirmed, it would be the first time a chemical weapon was used in Syria’s two-year-long crisis.
Washington said there was no evidence a chemical attack had taken place.
Syria’s state-run Al-Baath newspaper said that countries backing the rebels are indirectly responsible for the attack. The report said the use of such weapons changes “the rules of the conflict.”
British prime minister David Cameron said today that reports of a chemical attack in Syria strengthened the case for relaxing a Eu ropean Union arms embargo on the country, and warned that a failure to do so could lead to the kind of wartime massacres seen in Bosnia.
Britain and France are pushing for the EU ban to be eased to allow a flow of arms to outgunned rebels waging a two-year-old uprising against Syrian President Bashar al-Assad, but several EU countries and Russia oppose the move.
"The French president is concerned and I am concerned that we should not be restricted for months and months ahead when we don't know exactly what could happen in Syria, including the very worrying reports of use of chemical weapons," Mr Cameron told parliament.
The current arms embargo is part of a package of sanctions on Syria that expires on June 1st, but Britain and France have pushed to review the ban earlier.
Both countries tried in vain to convince other EU leaders to relax the embargo at a European Council meeting last week, and EU foreign ministers are expected to discuss the issue further at a meeting in Dublin Castle this weekend.
"I felt (while) sitting round the European Council chamber, there was a slight similarity between some of the arguments being made about not putting more weapons into Syria, that seemed to me very familiar to the discussions we had about Bosnia, and the appalling events that followed," Mr Cameron said.
Thousands of Muslim men and boys were killed in the Srebrenica massacre during the 1992-1995 Bosnian war, deaths many blamed on inaction by the international community.
Dr Assad is widely believed to have a chemical weapons arsenal.
Syrian officials have neither confirmed nor denied this but have said that if it existed it would be used to defend against foreign aggression, not against Syrians. There have been no previous reports of chemical weapons in the hands of insurgents.