Four UK businessmen fighting extradition to the US suffered a blow to their campaigns when the Law Lords refused to hear an appeal. The cases, involving the NatWest Three and Ian Norris, may now go to the European Court of Human Rights.

Four months ago the High Court cleared the way for a House of Lords appeal, which would have challenged the legal status of Britain's controversial fast-track extradition treaty with the US.

Yesterday, a committee of Law Lords refused a petition by former NatWest bankers David Bermingham, Gary Mulgrew and Giles Darby, and from Ian Norris, retired chief executive of Morgan Crucible.

Their cases have raised alarm among business leaders and human rights groups because of the low level of evidence US prosecutors have to show before they can seek the removal of a UK citizen.

Mark Spragg, solicitor for the NatWest Three, said the Home Office had allowed them seven days to apply to the European Court of Human Rights for a stay of the extradition order. "If we get a stay, the Home Office has agreed to abide by that pending the ECHR hearing of our full application," he said.

"We are surprised and disappointed by the [Lords] decision. It seems there are no safeguards to prevent people being extradited to the US."

Mr Norris's lawyer, Alistair Graham, said "The CBI, sIoD, the GC100, the Conservative Party, Liberal Democrats and human rights groups have voiced deep concern over the way extradition arrangements with the US are being used to target British business."