The roof at Royal Oldham Hospital is among dozens which need to be replaced over safety concerns.

A Government minister last month revealed more than 30 buildings across 16 NHS trusts are known to be affected – with £685m set aside to fix the problem.

Health minister Maria Caulfield did not reveal which hospitals were impacted but hospital bosses at the Northern Care Alliance, which runs Royal Oldham, have now confirmed reinforced autoclaved aerated concrete (RAAC) roof planks were used in constructing the roof of the main building at Royal Oldham.

They were also used in the roof of the Turnberg Building at Salford Royal, which the trust also manages, with no other sites at the trust affected.

A common material mainly used from the mid-1960s through the mid-1980s, RAAC is less strong than traditional concrete.

RAAC roof planks have caused the ‘sudden collapse’ of buildings in other parts of the country with ‘little warning,’ according to Cross, which publishes safety information for buildings.

A safety alert sent out nationwide in May 2019 says the useful life of the roof planks is estimated to be around 30 years, with the roofs of many buildings across the country now past their expected service life.

The NCA has insisted the Royal Oldham and Salford Royal planks have been checked and are in 'good condition'.

A Government document published last year by the Department for Education to help schools identify if they have RAAC roofs warned: "RAAC is less strong than traditional concrete and there have been problems as a result, which could have significant consequences."

Speaking to newspaper The Times, Caroline Shaw, NHS chief executive of The Queen Elizabeth Hospital in Norfolk, likened the material to a “chocolate Aero bar” with bubbles that could break and collapse at any point.

Andrew Montgomery, deputy director of estates, facilities and capital development at the Northern Care Alliance, said: “The planks in both buildings have been inspected as part of a national requirement for all NHS Trusts to monitor and identify any issues.

“The planks have been structurally assessed as being in a good condition and will be continually monitored using a range of assessment technologies.

“NHS England has committed to fully removing RAAC planks from the NHS estate by 2035.”

Responding to a Parliamentary Question tabled by Lib Dem MP Daisy Cooper, the health minister revealed the full extent of the problem in the NHS.

Ms Caulfield in her written response on July 19 stated: "The National Health Service has conducted building surveys to identify the presence of reinforced autoclaved aerated concrete (RAAC) in its estate. This identified 16 NHS trusts and 34 buildings containing RAAC planks.

"All affected trusts have employed structural surveyors to assess the condition of the infrastructure.

"A ring-fenced allocation of £110 million has been provided to mitigate the immediate risk and trusts will receive a further £575 million in the current Spending Review period."

It has led Liberal Democrat leader Sir Ed Davey to demand the Government urgently plan for emergency upgrades to the hospitals saying patients and staff are being put at risk.

Mr Davey said: “It is simply unthinkable that patients are being treated in buildings that could be at risk of collapse.

“We need to see urgent action from the government now to fix our hospital buildings and ensure the safety of patients and NHS staff.

“From record waiting lists to crumbling hospital roofs, patients are paying the price of years of Conservative neglect of our NHS.

"It’s time the government focused on actually delivering instead of making yet more empty promises.”

A  Department of Health and Social Care spokesperson said: “We are taking action to improve health infrastructure across the country, and have provided more than £4 billion for Trusts to support local priorities including to maintain and refurbish their premises, and have set aside over £685 million to directly address urgent risks relating to the use of RAAC in the NHS estate.

“The government is publicly committed to eradicating RAAC from the NHS estate by 2035 and protecting patient and staff safety in the interim period.

“The NHS will be approaching this on a risk basis prioritising NHS Trusts of concern.

“By 2030 we will have 40 new hospitals which will provide state-of-the-art facilities to ensure world-class provision of healthcare for NHS patients and staff by replacing outdated infrastructure.”

The pledge to build 40 hospitals has previously been criticised.