LONDON (Reuters) - A committee of MPs said Britain's extradition treaty with the United States is unbalanced, one-sided and in need of major changes, echoing recent criticism from politicians, campaigners and the media.

The 2003 treaty was signed to speed up the transfer of suspects between the two nations at the height of concern about terrorism after the September 11 attacks.

However, there have been growing complaints in Britain that the treaty is unfair. Prime Minister David Cameron has said it should be reviewed, and discussed the issue with U.S. President Barack Obama during his trip to Washington this month.

"The treaty is unbalanced, making it easier to extradite a British citizen to the USA than vice versa," Keith Vaz, chairman of parliament's Home Affairs Committee, said in a statement.

Controversy over the extradition arrangement has been highlighted by the case of British computer hacker Gary McKinnon, who was arrested in 2002 over what American officials called the "biggest military computer hack of all time".

McKinnon, who is accused of hacking into the Pentagon and NASA, suffers from Asperger's syndrome, a form of autism, and his supporters say he is too ill to be sent for trial in the United States, where he could face up to 70 years in jail if found guilty.

Other controversial cases include Richard O'Dwyer, a British student accused of running a website providing links to other sites that allowed users to access films and TV shows illegally, and Christopher Tappin, a British businessman accused of illegally exporting missile defence technology to Iran.

"The cases of Gary McKinnon, Richard O'Dwyer and Christopher Tappin have highlighted public concern that these arrangements are one-sided," Vaz said.

"Evidence to the committee has shown that the current arrangements do not protect the rights of British citizens. The government must remedy this immediately."

A judge-led review, however, concluded last October that the treaty was not biased against British suspects and that criticism of the treaty was based on a misunderstanding of how the legislation operated in practice.

But the committee said the treaty granted U.S. suspects the right to a hearing to establish a "probable cause" test, which was denied to British citizens.

It called for the treaty to be changed so the same test for extradition applied to both countries, and for judges to be allowed to decide whether a suspect should be tried in Britain in cases where both countries had jurisdiction.

In the longer term, the MPs said the treaty should be renegotiated to include a test of the evidence.

The Home Office said it would study the detail of the report before responding.

(Editing by Alessandra Rizzo)