The “enormous” profits being made by Private Finance Initiative (PFI) companies should be subject to a new windfall tax – so much-needed resources can be put back into cash-strapped public services, a union is urging.

Unison said such a tax could be introduced if two amendments to the Finance Bill, which have been tabled by Labour MP Stella Creasy, achieve enough support during Wednesday’s House of Commons debate on the draft legislation.

Unison said it believes a new windfall tax could prove a “lifeline” to under pressure public services and would force PFI firms to pay back some of the billions of pounds they’ve made “at taxpayers’ expense”.

Unisin general secretary Dave Prentis said: “Eye-wateringly high PFI payments are threatening to overwhelm our already cash-strapped public services.

“Local communities may now have shiny new schools and hospitals, but at huge cost. The repayments on PFI debt have to be made first, and are so steep that teaching assistants are losing their jobs and patient services are being cut back.

“Meanwhile, the shadowy PFI firms just keep on hitting the jackpot, making millions more than they’d ever hoped to because George Osborne slashed their tax bill a few years back.

“There’s no time to lose. Crippling PFI debts are pushing local services to the brink and costing taxpayers dear.

“It’s time for a windfall tax on the companies cashing in at our expense. It would bring some urgent and much-needed relief for the services we all rely upon.”