LONDON – A British computer expert accused by the United States of 'the biggest military hack of all time' lost an appeal on Thursday and could be extradited within weeks.

Gary McKinnon, 42, asked the European Court of Human Rights to block his extradition to the United States, complaining that he could face inhumane prison conditions if convicted there.

The court rejected the appeal.

McKinnon could face up to 70 years in prison if convicted of illegally accessing computers, including the Pentagon, U.S. army, navy and NASA systems, and causing $700,000 worth of damage.

'The appeal is lost,' said Karen Todner, of Kaim Todner solicitors, representing McKinnon. 'He is completely distraught, all of them are, his family, his girlfriend.'

Todner said her client would now appeal to Britain's Home Secretary (interior minister) Jacqui Smith to try to persuade her to reconsider an earlier decision and prosecute her client in Britain.

'Failing that he will be extradited...probably within the next three weeks,' Todner added.

Her client had recently been diagnosed with Asperger's Syndrome and hoped Smith would take this into account, she said.

McKinnon lost his appeal in July to Britain's highest court to block extradition to face charges in the United States.

He told Reuters in 2006 he was just a computer nerd who wanted to find out whether aliens really existed and became obsessed with trawling large military networks for proof.

His lawyers have argued that sending him to the United States would breach his human rights because he could be prosecuted on account of his nationality