MPs have demanded a rethink on Britain's extradition agreements, branding any deal that would send NASA hacker Gary McKinnon to the US as "lopsided".

Dominic Raab, the Conservative MP for Esher and Walton, said the government needed to impose tougher rules that would protect those accused of crimes abroad when there was a case against their extradition, the Daily Mail reported.

McKinnon has admitted hacking into NASA and the Pentagon, but said he was looking for evidence of UFOs. His mother and his supporters have argued he has Asperger's Syndrome, and would be at great risk of suicide if he we imprisoned in the US, where if he lost a case he could face a long sentence in a maximum security prison.

A review last month into the UK's extradition arrangements concluded that the system does not need to be changed.

The conclusion was met with some strong opposition including from MP Nick Du Bois who said it "fails to recognise the human reality".

MPs complain that much less evidence is required to extradite people to the US than the UK. "The fact is that, since 2004, 24 Britons have been extradited to the US under the new arrangements and just one American to Britain," Raab said, according to the newspaper. "The arrangements have been practically all one way."

Raab attacked "the absence of any discretion that allows the UK to decline extradition in cross-border cases having taken into account the interests of justice".

"That is the problem presented in the case of Gary McKinnon," he said, describing the hacker as "more misfit than terrorist".

Deputy prime minister Nick Clegg has said he will order a second inquiry into the extradition system.