Gary McKinnon has two more chances to save himself from being extradited to America, his lawyer said tonight.

Campaigners who have fought for almost eight years to prevent the 43-year-old computer hacker, who suffers from a form of autism, from being tried in the United States, were dealt a blow today when Home Secretary Alan Johnson refused to block his extradition on medical grounds.

Mr McKinnon faces up to 70 years in jail if found guilty of hacking into Pentagon computers soon after the 9/11 terror attacks. While he insists he was simply looking for evidence of UFOs the American authorities have likened him to a terrorist.

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"Each time there has been a change of Home Secretary I have had a glimmer of hope that someone will finally have the courage to intervene. I hoped that would be the case with Alan Johnson but that doesn't seem to have been the case," his lawyer Karen Todner said tonight.

However, she said that they had not given up hope and planned to apply for a judicial review within seven days. If the application is successful, the case should be heard within the next few weeks.

However, if it fails Ms Todner said they would apply to go before the European Court of Human Rights once again with the new evidence that Mr McKinnon had been diagnosed with Asperger's Syndrome.

"The ECHR would be our last option," she explained. "(The Home Secretary's decision) is a devastating blow but we are not going to give up. We are certainly coming to the end of the road. We're just hoping at some point someone sees sense and steps in.

"All the legal team do know is we cannot give up because in some ways it's like dealing with a Death Row case, and we genuinely believe that Gary's life is at stake here."

A host of high profile campaigners, who remain adamant he is too vulnerable to survive the rigours of the American penitentiary system, have insisted sending him to the US would be a travesty of justice.

But today Mr Johnson finally dashed hopes that the Government would intervene in the case, insisting there was no evidence that the extradition would breach Mr McKinnon's human rights.

His mother Janis Sharp said: "To force a peaceful, vulnerable, misguided UFO fanatic like Gary thousands of miles away from his much-needed support network is barbaric. This is a cruel and miserable decision."

The "naïve" computer hacker, who has attracted support from such high profile names as musicians Sting and David Gilmour, actress Julie Christie former home secretary David Blunkett and London mayor Boris Johnson, insisted he was merely motivated by curiosity when he hacked into 97 military computers at the Pentagon and Nasa between 2001 and 2002, searching for proof of UFOs.

However Mark Summers, an official representing the US government, told a London court that McKinnon's hacking was "intentional and calculated to influence and affect the US government by intimidation and coercion".