The future of 25 projects that are part of the New Hospital Programme in England is in doubt, after the government announced it would be reviewing their feasibility.

In a letter to MPs, Health Secretary Wes Streeting said it was clear the programme – promised by the Tories in their 2019 election manifesto – was “undeliverable and unaffordable”.

The government said 20 schemes would be able to proceed and would not be part of the review – but all options would be looked at for the remaining 25.

They include projects earmarked at Leeds General Infirmary, North Manchester General Hospital and Hillingdon Hospital, in Boris Johnson’s former consistency, Uxbridge and South Ruislip.

Some of the hospitals where the 20 projects free to proceed are located were built from reinforced autoclaved aerated concrete, which Mr Streeting said had to be “replaced as a priority to protect patient and staff safety”.

The letter said the government wanted the programme completed – but ministers were “not prepared to offer people false hope”.

Public finances were “incredibly challenging” – and with the estimated costs of the building programmes having risen by billions, it was clear not all the projects could proceed as planned.

The hospital-building programme, promised by Mr Johnson as prime minister, has already been beset by delays.

It originally included 40 hospitals but others were added over time.

The projects include complete new builds as well as major refurbishments or alterations.

Shortly after coming to power, Labour said it would be looking at the programme.

But it had not set out which projects would be at risk.

The review is being coordinated by the Treasury, Department of Health and Social Care and NHS England.

It is expected to be completed over the next month, in time for the Budget at the end of October.

The projects to be reviewed are at:

• Cambridge Cancer Research Hospital
• Charing Cross and Hammersmith Hospitals (London)
• Derriford Hospital (Plymouth)
• Eastbourne District General Hospital (Sussex)
• Hampshire Hospitals
• Hillingdon Hospital (London)
• Kettering General Hospital (Northants)
• Leeds General Infirmary
• Leicester General Hospital
• Milton Keynes University Hospital (Bucks)
• Musgrove Park Hospital (Somerset)
• North Devon District Hospital
• North Manchester General Hospital
• Princess Alexandra Hospital (London)
• Nottingham City Hospital
• Royal Berkshire Hospital
• Royal Lancaster Infirmary
• Royal Preston Hospital
• Shotley Bridge Community Hospital (Durham)
• Sutton Specialist Emergency Care Hospital (London)
• St Mary’s Hospital (London)
• Torbay Hospital (Devon)
• Watford General Hospital
• Whipps Cross Hospital (London)
• Women and Children’s Hospital (Cornwall)