Senior politicians from all parties are urging the home secretary, Jacqui Smith, to halt the extradition of the computer hacker Gary McKinnon unless she receives a guarantee from the US that he will be allowed to serve any sentence imposed in Britain.

The former home secretary David Blunkett is among those who believe that, because McKinnon has been diagnosed with Asperger's syndrome, he should be immediately repatriated if convicted.

In an early day motion, the shadow justice minister, David Burrowes, has urged Smith not to permit the extradition without assurances from the US that McKinnon would be repatriated to serve any sentence in the UK if found guilty.

Burrowes, the MP for the Enfield Southgate constituency in north London, where McKinnon lives, has alerted the home secretary to the "accepted practice" of the Dutch and Israeli governments requiring assurances from the US that any nationals with medical or mental health disabilities being deported to face trial should be repatriated to serve any sentence imposed.

Blunkett, who was in office when the 2003 Extradition Act was passed, said yesterday that he was supporting calls for McKinnon to serve any sentence in the UK because of his "special needs".

Burrowes's motion has already been supported by Chris Huhne, the Lib Dem home affairs spokesman, Chris Mullin, the former Foreign Office minister, and the Tory MP John Bercow.

Burrowes has also asked Harriet Harman, the leader of the house, for a debate on the proposed extradition. He noted that the house had debated the case of the NatWest Three, also known as the Enron Three, and asked Harman: "Can at least similar efforts be made on behalf of my constituent, who is a vulnerable young man of little means who was ... recently diagnosed with Asperger's syndrome?"

Lord West, the Home Office minister with responsibility for security, wrote to Burrowes last week telling him that "we reconsidered ... but found no grounds for overturning the order to surrender".

McKinnon has also had support from the leading constitutional lawyer Geoffrey Robertson QC. "Jack Straw bent over backwards to accommodate Pinochet's medical condition," said Robertson, in a reference to the decision not to extradite the late Chilean dictator because he had been diagnosed with Alzheimer's.

"It is highly unsatisfactory that this gifted and unusual British citizen should be extradited to face a massive sentence when he could have been prosecuted here before a British jury."

Lawyers acting for McKinnon, 42, are seeking a judicial review of the case.

McKinnon's mother, Janis Sharp, said: "Gary has Asperger's syndrome ... He believed the UK police when, almost seven years ago, they told him he would probably get six months' community service. Without having engaged a lawyer, he naively admitted to computer misuse but has always denied the alleged damage."