Hundreds of business leaders will march through London on Thursday to protest against the UK's "one way" extradition treaty with America.

The march has been organised by Karl Watkin, a dot-com millionaire, and has received the backing of the CBI's Sir Digby Jones and Shami Chakrabarti of the human rights group Liberty.

Mr Watkin said he was roused to action after the Law Lords refused to hear an appeal by four UK businessmen fighting extradition to the US last week.

Lawyers now hope the cases, involving the NatWest Three and Ian Norris, will go to the European Court of Human Rights.

Mr Watkin, who made ?3.6m from a ?30,000 investment in Just2Clicks in 2001, said: "It is the principle of it. If any businessman had signed such an unequal contract, he would be fired on the spot."

About 200 businessmen are expected to take part. A letter will be delivered to Home Secretary John Reid.

Among those marching will be Alex Worrall, chairman of Thyssen Krupp UK. Icap founder Michael Spencer is signing the letter.

The 2003 Extradition Treaty, which has not been ratified by the US, has been attacked after it was used to extradite business people for alleged white collar crime. It was intended to make it easier to send suspected terrorists across the Atlantic for trial.

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

It has emerged that unless the European Court of Justice responds swiftly and grants them temporary protection until their case is heard, extradition to the US could start as early as Thursday.

Mr Bermingham said: "Thursday's march needs the support of UK business."

Sir Digby said he was concerned whether British businessmen could get a fair trial in the US. "These are people who do not represent a threat to society."

A Home Office spokesman said Mr Reid declined to take a call from Sir Digby because "the Home Secretary did not think it is appropriate to speak about the cases when an appeal to Strasbourg was pending".

He added the "unbalanced evidential requirements" have been "redressed".