Lawyers for Gary McKinnon, the self-confessed hacker wanted in the US for corrupting dozens of military computer systems, have launched a last-ditch effort to prevent his extradition after losing a key court ruling on Friday.

Karen Todner, solicitor for Mr McKinnon, said she would send Alan Johnson, home secretary, fresh medical evidence next week showing that her client’s deteriorating health meant he should not be forced to stand trial in the US.