Hairmyres hospital is one of the new PFI hospitals

Researchers from Edinburgh University said the annual cost to the Scottish health service of PFI or PPP contracts will rise to �500m within five years.

Health Minister Andy Kerr defended PFI, accusing the report's authors of a "breathtaking lack of understanding".

The SNP said the study proved that private finance initiative had failed.

Under PFI, and its "public private partnership" (PPP) successor, a private sector consortium designs, builds and finances a health institution.

'Affordability gap'

However, they are controversial because firms make a profit from the scheme.

The study by the university's centre for international public health policy said the annual costs of PFI/PPP schemes would rise from �107m to more than �510m over five years.

The report argued that PFI buildings cost more than non-PFI buildings, creating an "affordability gap" that could be met only by switching money from clinical services, staff and supplies.

It said the finances of some health boards were under pressure, with NHS Lothian and NHS Lanarkshire paying out �46m and �41m respectively.

This leads to health boards having to spend a greater share of money meant for running costs on buildings, the report said.

Report lead author Mark Hellowell said: "Few people are aware of the scale of the Scottish Executive's plans to expand the PFI programme across the NHS.

The fundamental analysis of this report is ideologically driven Andy Kerr Health Minister

"The planned capital cost of �1.7bn will bring the total value of PFI schemes in the NHS to �2.2bn over the next five years.

"Health boards will have to find more than �500m every year to pay the annual unitary charge.

"Funds have to be found to bridge this gap and that can have very serious consequences for patient care."

Speaking on the BBC's Good Morning Scotland programme, Mr Kerr said it was wrong for the report authors to compare payments with the cost of traditional public finance, as costs applied over the whole lifetime of a contract and included upkeep and maintenance.

He denied that costs were five times what they would be under traditional public funding, insisting that projects were rigorously assessed for value for money.

Mr Kerr said annual payments would rise from more than �100m to �500m.

He added: "For that �107m, we have 28 projects, new hospitals where patients are being dealt with.

"The idea that we are somehow mortgaging our future and paying interest rates we should not be paying is just not true."

Patient care

He said the researchers appeared to believe the cost of hospital buildings was nothing to do with patient care.

"Their analysis assumes that you don't pay long term costs on publicly-funded projects, and that is wrong," he said.

"The fundamental analysis of this report is ideologically driven, in my view, and betrays a lack of understanding of public sector finance."

He said PPP would only go ahead if it was more cost-effective than the public sector option.

Tommy Sheridan has called for an inquiry into PFI schemes

The minister added that the executive had increased investment in the NHS from �4.9bn in 1999 to �10.3bn next year.

Over that period, he said capital spending had been �2.5bn, or 83%, through public funds and �520.6m, or 17%, under PPPs.

The leader of the Solidarity party has tabled a motion in the Scottish Parliament calling for an independent inquiry into the funding initiatives in the NHS.

Tommy Sheridan said: "Today we have the starkest warning that Labour's PFI chickens are coming home to roost - already �107m is going out of our health budgets to the banks and finance companies who are ripping us off and charging five times as much as it would have cost to rebuild our hospitals from public finance.

"Now we learn that it will rise to over �500m in five years and health services in Scotland will be seriously damaged.

"We urgently need an independent inquiry into the costs and implications of PFI for health care in Scotland before patients begin to die from the inflated cost of Gordon Brown's private finance schemes."