HMP Dovegate was put in lockdown while drug sniffer dogs and prison staff carried out a search of the residential wing.
They uncovered a huge haul of illicit substances, including heroin, cannabis and new psychoactive substances, formerly known as “legal highs”.
Eight improvised weapons, 36 mobile phones, 49 phone chargers and 17 SIM cards were also discovered during the raid, as well as spanners, super glue and drug paraphernalia.
It is understood the illicit items, described as a “significant find”, were discovered hidden inside of games consoles and inside trunking installed to protect water pipes.
The 1,060-capacity category B men's private prison at Marchington, near Uttoxeter, Staffordshire, is operated by Serco.
It opened in 2001 under a 25-year PFI contract.
HMP Dovegate was put in lockdown while drug sniffer dogs and prison staff carried out a search
The jail houses men who do not require maximum security, but who do pose a significant risk to members of the public.
We are working very hard to stop this illegal activity which is a major problem in all prisons
John Hewitson, Serco contract director at HMP Dovegate said the search on January 24 was carried out by prison officers who were acting on intelligence.
“This was a highly successful, intelligence-led operation by Serco staff that resulted in a significant find of contraband,” he added.
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“We are working very hard to stop this illegal activity which is a major problem in all prisons.” Staffordshire Police are understood to be investigating the incident but have so far been unavailable for comment.
Prisons minister Sam Gyimah said: “We're absolutely determined to tackle the illegal flow of drugs and mobile phones into our prisons and turn them into places of hope and rehabilitation.
The 1,060-capacity category B men's private prison is operated by Serco
“These incidents demonstrate the commitment our dedicated staff have in the fight against those who are attempting to thwart progress by wreaking havoc in establishments all over the country.
“My message to those who involve themselves in this type of criminal activity is clear: we will find you and put you behind bars if you persist."