LONDON - British Prime Minister David Cameron says British scientists have found new evidence that poison gas was used last month in a suburb outside the Syrian capital of Damascus.
In an interview with the BBC on Thursday, Cameron said that samples from Syria had been examined by experts at England's Porton Down Laboratory.
Cameron spoke from St. Petersburg, where world leaders have gathered for a summit and the Syrian government's alleged use of chemical weapons is expected to be high on the agenda.
A spokesman for Cameron's office said the samples consisted of clothing from one of the reported victims and soil taken from the area. He declined to comment on how or when the evidence made its way to Britain, citing security concerns.
Meanwhile, President Barack Obama pressed skeptical lawmakers to give him the authority to use U.S. military force against Syria during his overseas trip while the administration struggled to rally international support for intervention in an intractable civil war.
Ben Rhodes, Obama's deputy national security adviser, told reporters on Thursday that Obama was making calls to members of Congress while he attends an economic summit in St. Petersburg, Russia. The president spoke to a bipartisan group of five lawmakers on Wednesday.
"He is going to be doing outreach on the Hill," Rhodes said of the president's lobbying during the two-day summit in Russia.
U.S. Ambassador Samantha Power has lashed into Russia at the United Nations, accusing Moscow of holding the Security Council "hostage" by blocking action against Syria.
Power blames the structure of the Security Council, which lets five major nations hold veto power -- Russia, the United States, China, France and Britain. Russia has consistently used its veto power to block action President Bashar Assad's regime.
Power says "The system has protected the prerogatives of Russia, the patron of a regime that would brazenly stage the world's largest chemical weapons attack in a quarter century, when chemical weapons inspectors sent by the United Nations were just across town."
Power says Russia "Russia continues to hold the Council hostage and shirks its international responsibilities."