MPs urged the government on Monday to improve safeguards for British citizens wanted overseas and attempt to change the extradition treaty with the United States.

The MPs agreed in a parliamentary debate to call on ministers to bring forward new laws on British citizens wanted abroad, which could increase pressure on the government to press U.S. authorities for changes to the 2003 extradition treaty.

The agreed motion is not binding on the government, which has been criticised over contested cases such as that of three former British bankers jailed in Texas.

The bankers, known as the NatWest 3, were jailed in 2008 for their role in a fraud case related to the collapse of energy trader Enron. The three had lost a long legal fight against extradition to the United States.

Campaigners in Britain argue that the rules are lopsided and have taken up the case of British computer hacker Gary McKinnon, who was arrested in 2002 after allegedly hacking into U.S. security systems including the Pentagon and NASA and is trying to avoid being sent to the United States.

Critics in Britain say it is easier to extradite British citizens to the United States than vice versa, a claim rejected by U.S. Ambassador Louis Susman.

We believe that the existing US-UK Extradition Treaty works, is fair and balanced, promotes justice in both countries, and does not need to be changed, Susman wrote in the Daily Telegraph.

Susman said the differences were purely semantic.

In practice, the reasonable suspicion test is the same as the US's probable cause. They are the standards that police officers in our respective countries must meet to justify an arrest, he said.

Prime Minister David Cameron and his deputy Nick Clegg had raised the McKinnon case with U.S. President Barack Obama.

McKinnon who suffers from Asperger's syndrome, a form of autism, is too ill to be sent for trial in the United States, his supporters say. If extradition is granted he could face up to 70 years in jail.

Home Secretary Theresa May is weighing up medical evidence before making a final decision on his case.

A review of the extradition treaty in October led by retired judge Scott Baker found current extradition laws were not unbalanced, saying criticism of them was based on a misunderstanding of how the legislation operated in practice.

(Reporting by Philip Baillie and Stephen Mangan; Editing by Angus MacSwan)