A £4m-a-year lease for a prison that has been empty for 18 months has been a “needless waste of taxpayers’ money”, a report from MPs found.

The Public Accounts Committee (PAC) said the lease for HMP Dartmoor was signed by HM Prison and Probation Service (HMPPS) in March 2022 despite it being known the site had high levels of radon gas two years earlier.

The prison in Princetown, Devon, was closed in July 2024 after the government found levels of the radioactive gas were up to 10 times higher than the safe limit.

PAC said it did not accept HMPPS’ excuse that the lease needed to be signed due to a prison capacity crisis.

In its report, PAC said the lease – which cannot be terminated until at least 2033 – was signed without further comprehensive radon testing being carried out.

The report said a reduction to the annual rent or safeguards to mitigate the financial risks of increased radon levels were not negotiated and “poor commercial decisions” were made when the lease was signed.

PAC said improvement costs until the lease ends would cost £68m and neither the MoJ or HMPPS had clear plans for the prison’s future.

It added MoJ and HMPPS were now less than certain reopening the site represented best value for money.

Sir Geoffrey Clifton-Brown, PAC’s chairman, said the issue was an “absolute disgrace, from top to bottom”.

“Dartmoor appears to the Committee a perfect example of a department reaching for a solution, any solution, in a blind panic and under pressure,” he added.

“This is, obviously, not how policy should be delivered.”

PAC said once a plan for the prison had been decided, MoJ and HMPPS officials should assess whether they continued to spend money on the unoccupied site or consider negotiating an early exit from the lease.

It has also asked HMPPS to set out what it had learnt for the future from the “failures of its decision-making and contract management”.

A MoJ spokesperson said: “This government inherited a crisis in our prisons system, where prisons were on the brink of collapse, threatening a total collapse in law and order.

“This government is addressing the prisons crisis through building 14,000 new prison places, and the Sentencing Bill which will deliver punishment that works.”

The MoJ previously said the closure was temporary and the site had been made safe, adding it was working with specialist radon gas experts to “investigate whether we can reopen the prison safely”.