LONDON (Reuters) -Wikileaks founder Julian Assange has been denied permission to appeal at the Supreme Court against a decision to extradite him to the United States, the court said on Monday. While Assange’s extradition must still be approved by the government, Monday’s decision deals a serious blow to Assange’s effort to fight his deportation in the courts. U.S. authorities want Australian-born Assange, 50, to face trial on 18 counts relating to WikiLeaks’ release of vast troves of confidential U.S. military records and diplomatic cables which they said had put lives in danger. In December, …