The British High Court has ruled against a last-ditch bid by Gary McKinnon to avoid extradition to the US where he faces trial for hacking into military networks.

In a 41-page judgment, the judges ruled extradition was ‘a lawful and proportionate response to his offending’.

Outside court Mr McKinnon’s mother said: ‘We are heartbroken. If the law says it's fair to destroy someone's life in this way then it's a bad law.’

Whether or not Mr McKinnon can appeal further will be decided at a later date.

Lord Justice Burnton said it was a matter that should be dealt with ‘as expeditiously as possible’, probably in September.

Lawyers for the 43-year-old, who suffers from Asperger's Syndrome, were challenging decisions by successive British Home Secretaries allowing extradition to go ahead.

They also asked two judges to overturn a refusal by Keir Starmer QC, the Director of Public Prosecutions, to sanction a trial in this country. A UK trial would block extradition.

Mr McKinnon, from Wood Green, north London, and his supporters fear his medical condition, coupled with the stress of extradition and tough US prison conditions could result in psychosis and suicide.

Mr McKinnon was prepared to plead guilty to computer hacking offences to avoid extradition.

But former Home Secretary Jacqui Smith decided last October to order his removal following a request from the US prosecuting authorities.

The current Home Secretary Alan Johnson has insisted he has no power to demand the trial take place in the UK.

The US authorities say Mr McKinnon was responsible for the ‘biggest military hack of all time’, involving 97 government computers belonging to organisations including the US Navy and NASA.

Mr McKinnon has admitted breaking into the system in 2001-2 during a period of heightened security in the wake of the September 11 2001 attacks. But he claims he was looking for evidence of extra-terrestrial life.

The US government alleges his conduct was intentional and calculated to influence and affect it by ‘intimidation and coercion’. It says the cost of repair totalled more than $700,000 (€500,000)

Campaigners seeking to block his extradition say he acted through ‘naivety’ as a result of Asperger's - a form of autism that leads to obsessive behaviour - and should not be considered a criminal.