NEW : Syrian minister denies government forces used chemical weapons . The UN has said it is investigating the alleged use of sarin gas by President Bashar Assad's regime against its own people. If the claims that Syria used chemical weapons prove true , a speedy response will be needed to prevent another such attack , U.S. Defense Secretary Chuck Hagel said . The opposition says that Syrian forces used the nerve gas sarin as a weapon . UK prime minister talks with Canadian leader , U.S. president about `` all the options ''
NEW : Syrian minister denies government forces used chemical weapons . The UN has said it is investigating the alleged use of sarin gas by President Bashar Assad's regime against its own people. The opposition says that Syrian forces used the nerve gas sarin as a weapon . UK prime minister talks with Canadian leader , U.S. president about `` all the options ''