The Private Finance Initiative scheme, which is used by the government to build hospitals and health centres "off the books", will cost taxpayers over £27 billion this year, opposition MPs have claimed.
Figures published in the Chancellor's Pre-Budget Report put total payments between now and 2032 at £216.1 billion, compared with £188.6 billion at the time of the Spring Budget.
SNP Treasury spokesman Stewart Hosie said: "We have always known that PFI was hyper-expensive, but it is clear that the liability is rocketing out of control.
"Ironically, much of this money is owed to the banks the UK government has now bailed out. Labour has absolutely no financial credibility left."
He said that PFI "is a millstone round the UK's neck," and that if the Treasury had to put the money onto its own books it would add £216 billion to the national debt.
"We had hoped the Pre-Budget Report would set out when and how the UK government is going to bring PFI payments onto the books - instead we see the piles of secret debt mounting even higher," he said.
Other official figures show that the cumulative 25-year bill for PFIs has gone up by 74% since 2004, when it was £123.9 billion.