Tony Blair was drawn into the NatWest 3 affair yesterday and promised to try to help the three former bankers get bail while they await trial on Enron-related fraud charges in the US.
But the Prime Minister and John Reid, the Home Secretary, rejected pleas to block their imminent extradition.
In an open letter to Mr Reid, leading business figures, including the chairmen of GlaxoSmithKline, British Airways and the London Stock Exchange, urged him to "correct the mistake of a previous home secretary and preserve Britain's ancient tradition of transparent justice".
David Bermingham, Gary Mulgrew and Giles Darby have lost a two-year court battle against their extradition and are likely to be locked up in a high-security prison in Houston, Texas, for up to two years while they await trial. They are to be extradited by 17 July.
During Prime Minister's Questions in the House of Commons, Mr Blair defended the Government's new extradition arrangements with the US under which the men are due to be flown out. He denied the US was getting "preferential treatment".
Sir Menzies Campbell, the Liberal Democrat leader, asked him "what could be more unfair" than the extradition of three bankers without prima facie evidence under a treaty which had been ratified by the US. Laws rushed through in the aftermath of the 11 September 2001 terrorist attacks mean the US no longer has to present a solid prima facie case when making an extradition request while the UK still has to show "probable cause".
Mr Blair also said he understood the men's concerns and had asked his officials to see whether "any support or reassurance" could be given over the possibility of being bailed.
Legal experts say that because the bankers contested their extradition they would be deemed fugitives from justice and were therefore likely to be refused bail. Even so, the men are in negotiations with the US Department of Justice to secure a bail package that would allow them to come back to the UK to prepare their defence. Mr Bermingham said last week press coverage of the case "has been so embarrassing they [the US] consider it a major international incident".
The lawyer for the three men, Mark Spragg, ridiculed Mr Blair's promise. "Even bail conditions requiring the three's detention in the US will severely impinge their ability to properly prepare themselves for trail," Mr Spragg said. "To be bailed in Houston amounts to detention in a larger prison with prettier views. Not only would they be required to pay for their own living and housing expenses in the US, they would be prevented from working to earn their keep, let alone to help support their families ... All these issues fall away were they to be bailed to return to the UK to prepare for trial."
Their case was backed in an open letter to the Home Secretary in The Daily Telegraph yesterday which was signed by 39 businessmen and Conservative politicians. They included the retail tycoon Sir Philip Green, the former head of Vodafone and current chairman of GlaxoSmithKline, Sir Christopher Gent, British Airways' chairman, Martin Broughton, The London Stock Exchange's chairman, Chris Gibson-Smith, and the Telegraph Group chairman, Murdoch MacLennan, and Aidan Barclay.
They said the treaty was "manifestly unfair" and "highly damaging to our national interest". It added: "The Treaty is being used by the US legal system not to capture bombers but to bring to trial in America British business folk." The Home Office rejected the criticism, saying the legislation contains "robust safeguards against unfairness".
The bankers are accused of plotting with former Enron executives to siphon off $20m (£10.9m) from an Enron vehicle and pocketed $7.3m themselves. The US indictment alleges the trio advised NatWest to sell its stake in the company for $1m. The men deny the charges and want to be tried in the UK. NatWest's parent company, Royal Bank of Scotland, has not pressed any charges.