British interior minister Priti Patel on Friday approved the extradition of WikiLeaks' founder Julian Assange to the United States to face criminal charges, bringing his long-running legal saga closer to a conclusion.

Assange is wanted by U.S. authorities on 18 counts, including a spying charge, relating to WikiLeaks' release of vast troves of confidential U.S. military records and diplomatic cables which Washington said had put lives in danger.

His supporters say he is an anti-establishment hero who has been victimized because he exposed U.S. wrongdoing in conflicts in Afghanistan and Iraq, and that his prosecution is a politically motivated assault on journalism and free speech.