Plans to use private sector money to build and maintain six NHS hospitals worth nearly £1.5bn were approved by health ministers yesterday, prompting anger among public sector unions that foreshadows a revolt at Labour's annual conference in Manchester next month.

The six schemes, including facilities in health secretary Patricia Hewitt's constituency in Leicester, were scaled down to take account of the government's proposals for moving some services from hospitals into the community. This cut the cost by more than £400m.

Unison, the biggest public sector union, said the decision to build the hospitals under the private finance initiative (PFI) would prove "a costly error", locking NHS trusts into inflexible repayment obligations that would burden their balance sheets for 30 years or more. The union is expected to be heavily critical of NHS privatisation at the Labour conference.

The six developments took the hospital building programme since Labour came to power in 1997 to more than £10bn, almost all using using the PFI.

But the clarity of the government's message about NHS expansion was muddied by the results of a BBC investigation of hospital cuts planned in other parts of the country. It said these may involve the closure or downgrading of at least 10 big hospitals, but the Department of Health said nothing was finalised and preparations for "reconfiguration of services" were at an early stage.

The six schemes will be at:

· University Hospitals Leicester - a £711m development including a brand new women's hospital and a stand alone children's hospital at the Leicester Royal infirmary. The original proposals would have cost £906m.

· University Hospital North Staffordshire - £272m to build a community hospital and cancer centre.

· South Devon Healthcare - £163m to redevelop Torbay hospital, including a diagnostic centre offering MRI scans, more single rooms and day-case operating theatres.

· Walsall Hospitals NHS Trust - £140m for the complete redevelopment of the Manor hospital site.

· Salford Royal Hospitals - £112m for a new hospital with more single rooms, an enhanced A&E department and three new operating theatres.

· Tameside and Glossop Acute Services - £68m for three day-case operating theatres, new surgical wards and a 30- place day hospital for elderly mental health patients.

Andy Burnham, the health minister, said the facilities would become available from 2010. Up to half the beds would be in single rooms, in a shift away from large, public wards to more private accommodation. The schemes were revised to take account of the government's white paper on shifting care into the community, reducing the cost by more than £400m, he added.

Under PFI, hospitals are built and maintained by private companies, reducing the initial cost to the taxpayer. NHS trusts make repayments over 30 years or more.

Mike Jackson, senior national officer for Unison, said: "Using PFI to finance these schemes is a waste of taxpayers' money. PFI schemes are expensive, inflexible and adding to the current financial burdens of many hospital trusts."Andrew Lansley, the Conservative health spokesman, also criticised the PFI programme, saying it was in trouble as a result of financial mismanagement of the NHS.

The BBC survey suggested hospitals may be closed or downgraded in London, Surrey, Sussex, Greater Manchester, Lancashire and Cornwall. The Department of Health said: "In some areas there are too many hospitals providing the same, or similar services ... In those areas it is up to the local NHS to determine the best way ... to reconfigure those services.