A row has erupted over Government plans to offload hundreds of NHS properties to private developers — including at least three in Hertfordshire — prompting Labour to warn of a "flash sale" of the health service's assets.

Over 540 NHS properties — including dozens still used for clinical or medical purposes — totaling more than 1,300 hectares of land have now been deemed surplus to requirements, more than double the 546 hectares reported in 2016.

In the most recent report provided by NHS Digital, three plots of land belonging to Hertfordshire NHS trusts were listed as surplus and potentially eligible for sale, as part of wider Government plans to raise money for the health service.

Among those included on the surplus list are two plots of land in Hemel Hempstead, currently used for mental health and learning disabilities services, but which the Hertfordshire Partnership NHS Foundation Trust (HPFT) have proposed could instead be used for housing.

Of the two plots, one (found on Alexandra Road) contains office or administrative buildings while the other, at St Paul, houses buildings still used for clinical or medical purposes — just one among 117 nationally that Labour claims are still in medical use.

When approached for comment, a spokesperson for the HPFT confirmed the buildings were currently in active use by the trust, and was unaware of the proposals to place them on the market.

According to the surplus list, the local authority has not been consulted, despite the HPFT proposing to dispose of the properties in 2018, with planned market dates of December 2017 and January 2018 respectively.

A community treatment centre in Jackett's Field, Abbots Langley, is also proposed for sale, despite NHS Digital's data indicating that it is still being used for patient care — although a spokesperson for the Hertfordshire Community NHS Trust said that services were no longer being offered at the facility.

Details of many surplus plots have been kept confidential in cases where it is deemed that there are issues of sensitivity — for instance, where discussions with a potential buyer are ongoing — prompting fears that there could be yet more still in clinical use.

Two further NHS properties in Hertfordshire have already been sold to private developers, including part of the site of the old Queen Elizabeth II Hospital in Welwyn Garden City, which was closed in 2015, and buildings at the Eric Shepherd Unit in Abbots Langley, sold in 2015 for over £2.5 million.

Doug Swanney, chairman of North East Hertfordshire Labour Party, said he was "extremely concerned" about the sale of NHS land, adding: "NHS property is being sold-off across Hertfordshire, causing people to travel further for treatment and wait longer for appointments.

"After years of Conservative budget cuts, our NHS urgently needs properly funding, but the answer mustn't be a blanket sell-off of public land.

"NHS Trusts are effectively threatened with punishment if they fail to find property to sell and rewarded if they do, when these decisions should be made with patient care uppermost.

"As NHS spending on independent sector provision grows each year, how can we be sure that the money raised will actually go towards maintaining our hospitals or caring for patients?"

Mohammad Yasin, Labour MP for Bedford and Kempston, said: "I'm not necessarily opposed to the disposal of property where it is unsuitable for modern medical use, but there will undoubtedly be plenty of valid clinical uses for much of the land up for sale.

"Locally we need acute mental health beds for example - where will these go if all NHS land is sold?

"Land isn't genuinely surplus if there is an unmet need, and disposing of it in what amounts to a fire sale risks getting very poor value.

"This Government and the last are renowned for this - look at what they did with Royal Mail.

"If land in public ownership is being sold on the cheap to plug a hole in NHS finances, then that would be completely wrong - and it looks like this is exactly what is happening."

Hertfordshire Partnership NHS Foundation Trust claim that community services currently offered at the Alexandra Road and St Paul's sites will be moved to newly-refurbished facilities at The Marlowes, with building work having begun in May and a phased transition period due to begin at the end of the year.

In a statement, the Trust said: "We are currently transforming The Marlowes site in the centre of Hemel Hempstead into a modern, state-of-the-art building where both NHS mental and physical health services will be provided in an integrated care setting with very good public transport links.

"We need to use our buildings as efficiently as possible and the longer term future of the buildings remains under consideration.

"The end result will be services delivered in a building that will be a great environment to receive care.

"We will develop new ways of providing care and treatment, supporting our service users to look after both their physical and mental health and well being."