A British man who has been accused of perpetrating "the biggest military hack of all time" should be extradited to the US, a British court has decided.

Gary McKinnon is accused by the US government of causing £370,000 worth of damage by breaking into several American military computer systems.

He says he was not acting out of malice but was trying to expose what he thought was poor security and to investigate secret information on UFOs.

He was arrested in 2002 by the National Hi-Tech Crime Unit, which is now part of the Serious Organised Crime Agency.

However, the American government did not question him about his alleged crimes until 2005. At the same time, the US began extradition proceedings against him.

John Reid, the newly-appointed Home Secretary, now has to decide whether to grant the extradition. McKinnon can still appeal to the High Court and the Law Lords if the decision goes against him. He could face up to 70 years in jail if convicted.

The 2003 Extradition Act allows British suspects to be sent to America to face trial without American prosecutors having to disclose their evidence.

At McKinnon's extradition hearing, prosecutors gave the court a note saying that McKinnon would not be treated as a foreign terrorist once he arrived in America, but his defence lawyers argue that, as the note is not signed, it may not be binding.

McKinnon told the court that he fears being sent to the Guantanamo Bay terrorist detention camp.

Other British hackers have rallied round McKinnon, saying that he is being made a scapegoat and that the case is being used for political ends rather than for improving computer security.