A British hacker who broke into US military computers looking for evidence of UFOs lost another extradition appeal on Tuesday in London's High Court.

Gary McKinnon, of London, remains free on bail and could appeal the decision to the House of Lords, according to a High Court spokesman.

He is accused of deleting data and accessing information on 97 US military and NASA computers between February 2001 and March 2002. He was charged in the US District Court for the Eastern District of Virginia and could face up to 60 years in prison.

McKinnon challenged an initial extradition order in May 2006. His attorney fought the order on the grounds that his client could be held as an "enemy combatant," a status the US created for terrorism suspects. Home Secretary John Reid approved the extradition order, however, and McKinnon appealed again.

He freely admits to hacking into the computers but says he never caused any harm. US officials, however, say his probes caused $700,000 in damages and the shutdown of critical computers used by the military after the 11 September, 2001, terrorist attacks.

The soft-spoken McKinnon said he timed his hacking when no one was working at the US offices. On one occasion he miscalculated the time zones, however, and someone using a computer that McKinnon had hacked noticed the cursor moving on its own.

McKinnon used a program called "RemotelyAnywhere" to control the computers. Many of the computers he accessed were set up with their default passwords, which made them easy to access, said McKinnon, who spoke at a security conference in London last year while his appeal was underway.

McKinnon did not immediately return a call seeking comment.