Incentives have been offered to keep consultants in the NHS

About 3,000 consultants in Scotland were changing to the new contract on Thursday, which is designed to help them to manage their workload better.

The arrangement offers them higher pay for dedicating their overtime to the NHS rather than the private sector.

But the cost of the deal could plunge several health boards deeper into debt.

BBC Scotland has found that NHS Lothian faces a bill of about £8m for the new contracts - £5m more than managers were expecting.

And Glasgow's health board said that although final figures have not yet been worked out, costs have doubled, as has been the case elsewhere in the country.

The British Medical Association (BMA) said the figures were higher than expected due to a mistake in the accounting.

Some sources said this has been down to confusion over the number of hours consultants actually work.

Two years of negotiations were needed before the new contract was finally proposed in September 2002.

The costings [that were done previously] were not absolutely correct Malcolm Chisholm Health minister

It offered higher pay in return for working core hours which includes evenings and weekends, and more overtime for the NHS rather than the private sector.

The increasing costs surrounding the new deal could result in some health boards having to pull out of other planned areas of investment.

Dr Peter Benny, a consultant psychiatrist at Parkhead hospital in Glasgow, told BBC Radio Scotland that the contract change was "a time of great uncertainty for consultants in Scotland".

He said: "The new contract is supposed to come in on Thursday, but not one consultant has that new contract yet.

"It is supposed to recognise the amount of hours doctors across Scotland work - surveys show between 46 and 50 hours a week.

"The old contract pays us for only 38 and a half and that will still be the case until this new contract actually comes in, which may be another month or two yet.

"Our pay may well be being backdated to April, but it's certainly not being backdated the 10 or 15 years that people have been working these hours."

He added: "The delay in bringing the new contract in really seems to be about difficulties employers have in introducing it. They have known since October last year the exact details of it, but here we are in April and not one consultant has been able to sign up to it yet."

'Exciting process'

Dr Brian Cowan, medical director of Greater Glasgow NHS Board, defended the delay.

He said: "This is one of the most radical changes in contract in NHS history, that means that in Glasgow we've had to do almost 1,000 different individual job plan negotiations."

Health Minister Malcolm Chisholm admitted that there will be at least a two-month delay before the new consultant contracts are all in place as the job of each individual doctor has to undergo assessment.

Speaking on BBC Radio Scotland, he said: "We must get the job plans of consultants correct, there is a lot of extra money going to consultants - quite rightly - but in exchange for that consultants must give a proper account of what they do, they must guarantee the hours they spend in hospitals and they must put their NHS work first."

Mr Chisholm also admitted that the new contracts were turning out to be "a bit more expensive than originally envisaged."

He added: "The costings [that were done previously] were not absolutely correct.