The scale of drug abuse and violence at HMP Birmingham meant many of the perpetrators faced no sanctions and staff locked themselves in their offices in fear of prisoners, a report has said.

Inspectors found prison officers were “anxious and fearful” and were regularly targeted for attacks including arson. Officers were found asleep during lock-up periods by inspectors and several locked themselves away.

The shocking details in the report include:

Inmates faced ongoing intimidation, including other prisoners squirting urine or throwing faeces through broken observation panels.

A vulnerable and distressed man found sitting on the springs of his bed told inspectors his mattress had been stolen three days earlier.

A troubled inmate struggling with personal hygiene issues was repeatedly sprayed with water from a fire hose by other inmates who soaked him and his possessions, in what the report described as “appalling bullying”.

One in seven prisoners said they had developed drug addictions during their time inside prison.

Staff frequently lost track of prisoners, the report said, and in at least one case a prisoner who had been moved to another wing because of his intimidating behaviour found his way back to his old wing unchallenged.

The smell of cannabis hung in the air and some prisoners were evidently under the influence of drugs. Testing revealed a third were using illicit substances, and trafficking was blatant, the report said. At least three recent prisoner deaths are likely to have been caused by the use of synthetic cannabis.

“I have inspected many prisons where drugs are a problem, but nowhere else have I felt physically affected by the drugs in the atmosphere – an atmosphere in which it is clearly unsafe for prisoners and staff to live and work,” Peter Clarke, the chief inspector of prisons, wrote to the justice secretary, David Gauke. “When inspectors at one point raised the fact that drugs were clearly being smoked on a wing, the response from staff was to shrug.”

Timeline G4S scandals since 2010 Show Jimmy Mubenga, 46, an Angolan deportee, dies after being restrained and held down by three G4S guards on a British Airways flight due to depart from Heathrow airport. The guards are later cleared of manslaughter. The Serious Fraud Office investigates G4S for alleged overcharging for tagging criminals in England and Wales, claiming it charged for tagging people who were still in prison, out of the country or dead. The firm is later cleared of fraud but agrees to pay a settlement of £109m. Six members of staff are dismissed for gross misconduct at the G4S-operated Rainsbrook secure training centre for children in Rugby. An Ofsted inspection found some staff were on drugs while on duty, colluded with detainees and behaved “extremely inappropriately”. G4S loses the contract later that year. Eleven members of staff at Medway secure training centre are suspended or sacked after a BBC documentary alleges staff inappropriately restrained inmates and falsified statistics to improve the facility’s record. At least 10 arrests are made. Later in the same year, hundreds of prisoners at the G4S-run HMP Birmingham take part in a riot, blaming poor staffing levels, food and medical care and being kept on lockdown in their cells all day. The government takes control of Birmingham prison after a damning inspection found inmates used drink, drugs and violence with impunity and corridors were littered with cockroaches, blood and vomit.

The report describes a squalid environment where self-harm was endemic and conditions filthy and degraded. Vermin and cockroaches were widespread, inspectors found, and blood and vomit was left in hallways uncleaned, as well as rat droppings.

“I saw a shower area where there was bloodstained clothing and a pool of blood that had apparently been there for two days, next to numerous rat droppings,” Clarke wrote. Cells had exposed wiring and broken windows; prisoners slept in freezing conditions.

The inspectors raised grave concerns about high-risk prisoners due for release, with 50 due to be freed between August and November this year. “We were greatly concerned that measures to protect the public from those men – while in prison and on release – were very poor,” the report says.