The Government defeated attempts to block further "fast-track" extraditions to the United States last night despite a back-bench Labour rebellion in the Commons.

The Government successfully overturned additional safeguards introduced by the House of Lords in July at the height of the controversy over the extradition of the 'NatWest Three' to stand trial on fraud charges in America.

A bid to strike out the United States from fast-track extradition arrangements was rejected by 320 to 263, a majority of 57.

Mr Blair's 62-strong majority was cut to 41 in a second vote on a call by peers for extradition to only go ahead where it was "in the interests of justice". MPs voted 313 to 272 to reverse the Lords amendment to the Police and Justice Bill.

Peers had wanted the United States removed from the list of approved countries from which evidence was not required before an extradition request was granted.

Business leaders and civil liberty campaigners had lobbied MPs to back the changes introduced by the Lords to protect UK citizens from "unjust extradition proceedings".

Critics say the treaty is unbalanced and gives British nationals less legal protection than people in other countries. US authorities need to outline the alleged offence and provide information that would justify the issue of a warrant for arrest in the UK. However, Britain must provide the United States with evidence of "probable cause", a stronger standard than "reasonable suspicion", if it wishes to extradite someone.

The NatWest Three - David Bermingham, Gary Mulgrew and Giles Darby - were extradited under the terms of a US-UK treaty designed to make it quicker and easier to deal with people suspected of cross-border offences such as terrorism and organised crime.

Joan Ryan, a junior home office minister, told MPs the Lords' amendment would "wreck our ability" to bring fugitives to justice.

She insisted that there was "rough parity" in the arrangements applied since 2003, and the changes introduced by "misguided" peers were a "bad day for international cooperation in the fight against crime".

Faced with interruptions from all sides, she tried to placate critics by announcing that the Attorney General, Lord Goldsmith, had opened discussions with his US counterpart about cases which ought to be heard in the UK.

"Discussions are now under way between their respective offices on enhanced procedures for consultation between the UK and US prosecutors on such transnational cases."

Miss Ryan said Britain was "dealing with a trusted partner with a legal system of long standing".

"We have extradited people to the US, and they to us, for 100 years. We trust their system just as they trust ours."

Robert Marshall-Andrews, the Labour MP for Medway, denied there was "reciprocity" between the two systems, insisting the arrangements for extradition were "unequal".

John Redwood, a former Tory minister, said many Conservatives were sympathetic with the extradition arrangement for terrorism. But he questioned whether it was right to use the powers for so-called white collar crime where individuals could be "plucked away from their family for a very long time on a charge we don't think will go anywhere".

Edward Garnier, the Conservative home affairs spokesman, said the Government's opposition to the amendments was "unjust, unfair, undemocratic and damaging to the interests of this country and our citizens".

The 2003 treaty was signed by the two governments without prior notice to the Commons. "It was negotiated and signed behind our backs," Mr Garnier said.