The United States and Britain are "in no doubt" that the regime of President Bashar al-Assad used chemical weapons in an attack in Syria last week, dpa reported.
British Prime Minister David Cameron spoke by telephone to US President Barack Obama late Tuesday, "to hear the latest US thinking on the issue" before holding a meeting of the National Security Council (NSC), the spokesman said.
"They both agreed they were in no doubt that the Assad regime was responsible," he added. "Regime forces were carrying out a military operation to regain that area from the opposition at the time, and there is no evidence that the opposition has the capability to deliver such a chemical weapons attack."
Senior ministers, intelligence and military chiefs are to attend the NSC meeting on Wednesday. The government is also expected to publish a motion on its response to the crisis for parliamentary debate on Thursday.