Inspectors say drug use at supersized G4S jail is more than twice rate in similar prisons

Prisoners claim it is easier to get hold of illicit drugs than a bar of soap inside Britain's largest prison, G4S's flagship Oakwood jail near Wolverhampton, according to official inspectors.

The chief inspector of prisons has confirmed that drug use at the 1,600-place privately run "supersized" jail, which opened in April last year, is more than twice the rate of similar jails while inmates find it difficult to get hold of clean prison clothing, basic toiletries and cleaning materials.

One in seven inmates report having developed a drug problem while they have been inside Oakwood.

Nick Hardwick, the chief inspector of prisons, says in Oakwood's first official inspection report published on Tuesday that a retrieval plan for the prison is urgently needed and there are real risks if matters are allowed to drift.

He says the inexperience of the prison staff is evident throughout the jail, with many passive and compliant to the point of collusion to avoid confrontation with the prisoners: "There was clear evidence of staff failing to tackle delinquency and abusive behaviour," the report says.

Despite the drive by the justice secretary, Chris Grayling, to introduce a full 40-hour working week across the prison system, the majority of the 1,600 inmates were not fully employed, with more than a third of them locked up in their cells during the working day.

The prison inspectors who made an unannounced two-week visit to the jail in June say that "on more than one occasion we were told by prisoners that 'you can get drugs here but not soap'".

Nearly 20% of the jail population tested positive for drugs or refused to take the test and the ready availability of drugs and "hooch" – homemade alcohol – is at twice the level of similar jails.

The inspectors identified the main illicit drugs in use as Black Mamba – a class B synthetic "herbal" mixture that imitates the effects of cannabis – Subutex, an opioid, and heroin. They said there was also strong evidence that some prisoners were injecting diverted prescription drugs including insulin and steroids.

The level of drug use is matched by high levels of assaults, victimisation and bullying, with too many prisoners feeling unsafe, including those housed on the vulnerable prisoners' wing, inspectors found.

The use of force to restrain inmates was twice as high as at similar jails, with 241 incidents in the first six months of this year.

The inspectors also identified weaknesses in the reception processes at the jail: "One prisoner had been noted in his secondary screening on arrival as having 'no disabilities'. In reality, he was unable to walk without a Zimmer frame and was partially sighted and deaf."

Hardwick said: "There is a lot to do before Oakwood is operating anywhere near effectively. Positively, the prison is an excellent facility. We found a management and staff team that were working hard and seemed keen to do the right thing. But the prison urgently needed a plan to retrieve the situation and there were real risks if matters were allowed to drift. Prisoner frustration needed to be addressed. Systems that delivered basic services had to be made to work."

Jerry Petherick, of G4S custodial and detention services, said opening the largest prison in the country was always going to be a challenging operation with prisoners testing the regime as well as the staff, who might be new to prison life.

He said a dedicated task force had been set up to tackle the drugs problem, which was starting to yield results: "We do not underestimate the effort which will be required to bring Oakwood up to the standard we have achieved at our other prisons," he said.

Michael Spurr of the national offender management service added: "The chief inspector has made clear there is much more to do to achieve the high standards we expect but operating systems are now fully established and I am confident that the improvements will be achieved. We will work with G4S and continue to monitor performance at Oakwood closely over the coming months."