Boris Johnson’s flagship election pledge to build 40 new hospitals by 2030 will undergo a probe by the official audit watchdog.
The National Audit Office plans a "value for money review" that could consider rising costs due to inflation - and whether the hospitals will in fact be new.
The investigation emerged in a letter to Shadow Health Secretary Wes Streeting from NAO comptroller Gareth Davies after the Labour MP warned of a waste of taxpayers' money.
In the letter first reported by the Observer, Mr Davies said: "I can confirm that I already have plans to start a value for money review of the New Hospitals Programme later this year and to report my findings during 2023.”
Part of the investigation could include “whether all projects truly meet the classification of 'new hospitals'”.
The Conservative manifesto clearly stated they would "build and fund 40 new hospitals over the next 10 years". But some of the 40 ‘new’ hospitals will be extensions while others may only feature redecoration of existing facilities.
When a list of 32 of them were published in October 2020, one - the Royal Liverpool - was already supposed to have been completed in 2017.
Others included “rebuilding” Watford General Hospital, a “new hospital at” an existing site in Whipps Cross, North London, and a “rebuild at” Leicester Royal Infirmary.
A string of other projects were also described as “rebuilds” by the government at the time.
Meanwhile not all 40 had funding confirmed straight away. While 10 smaller schemes are due to start before September 2024, eight larger projects that should be completed no later than 2028 have yet to be given a start date, according to the Sunday Times.
Mr Streeting had asked for an investigation into delays surrounding the programme announced by the Prime Minister in the 2019 general election campaign.
The Labour MP said many NHS trusts are still awaiting funds to be allocated and many are in fact alterations or refurbishments not "new hospitals".
In his reply Mr Davies added: “I have passed your letter to my Health Value for Money team so it can consider the specific issues you raised as it develops the scope of the review.
"In particular, I note your comments about the implications of delay for increasing costs at this time of high inflation and the matter of whether all projects truly meet the classification of 'new hospitals'."
The NAO's work threatens to cast further doubts over Mr Johnson's ability to deliver on his promises, as he fights a series of scandals including partygate and allegations of sexual misconduct levelled at Tory MPs.
Commenting on the investigation, Mr Streeting said: "The only place these '40 new hospitals' currently exist is in Boris Johnson's imagination.
"The election manifesto promise now looks to be another example of the Conservatives overpromising and underdelivering."
The Department of Health and Social Care insisted: "We are on track to deliver 40 new hospitals by 2030.
"We are working closely with the NHS and trusts on the development of their building plans. Each of the building projects will be new hospitals providing brand new, state-of-the-art facilities to ensure world-class provision of healthcare for NHS patients and staff by replacing outdated infrastructure."
