UNISON is calling for the “enormous” profits made by private finance initiative (PFI) companies to be made subject to a new windfall tax to provide “much-needed relief” for public services.

The union said the tax could be introduced if two amendments to the Finance Bill achieve enough support in the House of Commons on Wednesday.

Unison’s general secretary Dave Prentis said a windfall tax would be a “lifeline” to under-pressure public services and would force PFI firms to pay back some of the billions of pounds they have made “at taxpayers’ expense.”