Three UK bankers today exhausted their efforts to avoid extradition to the US where they face fraud charges in connection with the Enron scandal.

David Bermingham, Gary Mulgrew and Giles Darby are likely to be flown to the US next month after the European court of human rights (ECHR) in Strasbourg rejected their request for a delay in their extradition.

The former NatWest bankers, who have said they are innocent and should be tried in Britain, now face trial in Houston, Texas where the bankrupt US energy firm was headquartered.

In a letter to the London law firm Jeffrey Green Russell, the ECHR said it saw no immediate cause to overturn the decision of the British courts to send the trio for trial in the US.

A court official wrote that it had been decided "in the circumstances, not to indicate to the government of the United Kingdom ... the interim measure you are seeking".

Today's setback for the trio came after the House of Lords last week threw out their request to appeal against an earlier verdict from the high court which said the men could be tried in the US.

"We have now done everything possible to establish the rights of three UK citizens to be investigated and, if appropriate, prosecuted in the UK but all we have established is that UK citizens have no such rights against an extradition request made by the US," said the men's lawyer, Mark Spragg.

The case has sparked anger and concern among British business leaders and human rights campaigners, who have criticised the use of a new extradition treaty originally designed to target terrorist suspects after September 11. They have also criticised the unsymmetrical nature of the treaty.

Under the treaty, the US is able to demand a Briton's extradition without having to show there is a case to answer based on available evidence. In contrast, Britain has to prove its case in a US court to extradite US citizens to the UK. The US has still not ratified the treaty.

Commenting in light of the ECHR ruling on the Natwest 3, Sir Digby Jones, director-general of the CBI, said:

"There is no prima facie case against these three men. They represent no threat to society yet they will still be banged up in a US prison with rapists and drug addicts, deprived of their liberty for up to two years, even while a case is compiled against them. If targeted in Britain for the same offence they would remain on bail and keep their liberty up to and during the trial.

"This is not about going soft on white-collar crime. If these three are guilty, they should be treated just as those responsible for any other crime. But guilty or not, they should be treated fairly.

"The prime minister told the Commons in March this year that the he did not accept the rights of British citizens were subject to unfairness through this treaty, but it is manifestly the case. I urge Tony Blair to intervene to defend the human rights of British citizens that are being abused by a country which is supposedly our greatest ally."

The three bankers who worked for NatWest Bank, now part of Royal Bank of Scotland, are alleged to have conspired with Enron executives, including Enron's former finance director, Andrew Fastow, over the sale of a stake in an Enron entity in 2000 for less than it was worth, which made them $7.3m (?4m).

Enron filed for bankruptcy in 2001 after revealing that it inflated its profits and filed false accounts to hide debts.