GLOUCESTERSHIRE Constabulary has been left red faced after brazen thieves stole copper piping from a new £12.5 million custody suite being built next door to the county police HQ at Waterwells.
Criminals targeted the cell block twice in three days.
They first raided the construction site in Quedgeley on Monday, August 18 and then again three days later - avoiding detection on both occasions.
A spokesman for Gloucestershire police said: "We can confirm that a very small quantity of copper was stolen in two incidents at the new police custody block which is still being built at Waterwells.
"The building is still in the hands of the contractor and not yet handed over to Gloucestershire Police.
"At no point was any sensitive information at risk since the building is still not in use and contains no police information of any kind.
"The cost of the loss will be borne by the contractor and the project has not been delayed at all.
"Police are working closely with the contractor to investigate these incidents and to advise them on any recommended security measures."
The new cell block will replace ageing and outdated cells at Gloucester and Cheltenham police stations.
Police and Crime Commissioner Martin Surl approved the scheme at a governance board meeting earlier this year after capping the cost at nearly £12,500,000.
It will be capable of housing up to 50 detainees in secure accommodation, with CCTV in every cell to monitor them at all times.
It will also allow shorter admission waiting times and mean a quicker turnaround of police officers back onto patrol Construction work is due to finish by the end of this year.
Anyone with information about the thefts should call 101 quoting incident numbers 237 of 18 August and 94 of 21 August and crime number 19094/14.