The government's new IT system for the NHS is two years behind schedule and could cost up to £20 billion, Lord Warner has admitted.
The health minister said that although the contracts to provide the new programme were to budget, about £6.2 billion, the cost of staff training, buying computer equipment on the ground and bringing existing IT systems together would substantially raise the cost.
The NHS currently spends about £1.6 billion a year on IT, and given that the full project will not be available until 2007 or 2008, Lord Warner said the cost could reach £20 billion.
However, he told the Financial Times that this "has always been the case" - and noted that the health service would have been spending about £1 billion on old systems anyway, which provided none of the benefits of the new scheme.
His comments come as a survey for BBC News finds that while four out of five GPs have access to a new electronic booking system - choose and book - which is part of the IT programme, just one in five said they thought it was good or fairly good.
Half said they rarely used the system, and almost two thirds thought the whole of the Connecting for Health programme was not a good use of NHS resources.
As well as the booking system, which should allow patients to book hospital appointments from GP surgeries, the programme includes a new electronic database of patient records, and electronic prescriptions.
One of the reasons for the delays to the programme, Lord Warner told the newspaper, was disagreement with the medical profession about what information would be on this new database.
Originally, ministers proposed that major diseases, operations and current medications and allergies would be recorded, although it appears that the first wave of data will only include information on allergies and drugs.
A report due to be published next month by the National Audit Office (NAO) is expected to criticise the Department of Health for failing to properly consult with health staff on the IT upgrade, and Lord Warner today admitted this was "a fair criticism in part".
"We possibly could have got into the game earlier, and we could probably have done it better earlier on," he said, but added that doctors wanted to "see the reality" before they got fully involved, and this was now happening.
He concluded: "I don't feel apologetic about some of the missed targets. If you don't set some ambitious timetables you will not drive a big project of this kind."
However, the Liberal Democrats said the admission of the extra cost and delays was "shocking", and questioned what impact they would have on NHS trusts already struggling with millions of pounds in deficits.
"Hospitals need to know exactly when the system will be delivered so that the transition will not affect patient care," said health spokesman Steve Webb.