Lambert and Digby Jones at odds over NW3

Richard Lambert, the new director general of the CBI, yesterday weighed into the escalating debate over the NatWest Three - who are facing extradition to the US on Enron-related fraud charges within a fortnight - and attacked the Government's extradition regime.

But he publicly disagreed with his predecessor Sir Digby Jones, who retired as CBI director general at the weekend, by saying that it would be wrong to pin any blame on NatWest's parent company, Royal Bank of Scotland, for not intervening in the case.

Mr Lambert said: "The people in the dock over this are the British government, which signed a treaty with the Americans that allows them to charge people in this country with alleged offences committed in this country and take them off to the US." He added: "I think this is a question for the Government. The Government signed the treaty ... RBS has a broad set of interests that it has to protect. I think it is wrong to point the finger at them."

At the weekend, Sir Digby claimed several RBS business customers were planning to protest to Sir Fred Goodwin, the chief executive of RBS, over the bank's failure to "defend the three and explain its position." Sir Digby's criticism of RBS has raised eyebrows in the City as he starts a new job next month as a senior adviser to Barclays Capital, the investment banking arm of RBS's British rival Barclays. He has been appointed to develop the bank's client relationships in the UK and internationally.

RBS reiterated yesterday that it "continues to reserve its rights against the three". A spokeswoman added: "Extradition issues are a matter for the Government and the courts to determine. We have co-operated fully with all the relevant parties and made them fully aware of all relevant facts in our possession."

The bankers are being extradited under new laws which were originally designed to fast-track terrorism cases, but critics believe they are being abused by US authorities to trap white collar criminals.

The trio - David Bermingham, Giles Darby and Gary Mulgrew - are accused of plotting with former Enron executives to defraud the energy giant of $20m, pocketing $7.3m themselves. According to the allegations, the three advised NatWest in 2000 to sell its investment in an Enron business for $1m, less than it was worth, yet the Edinburgh bank has not pressed any charges. Enron then paid $30m into the vehicle, believing NatWest would receive $20m.

During the bankers' two-year court battle against extradition, it emerged that the Financial Services Authority had asked RBS to revalue its investment in the Enron company at the time of the sale which "resulted in a figure very much in line with the original", according to the FSA report. The regulator decided not to investigate further.

Mr Bermingham has accused Sir Fred of turning a blind eye to the men's plight when it was within his power to help, suggesting the bank cared more about its US business interests.