Detainees and staff at Britain's newest immigration removal centre are frequently the victims of bullying and violence, a damning report concludes.
The investigation by Anne Owers, the Chief Inspector of Prisons, also found that drugs were widely available at the detention centre near Gatwick airport, which only opened a year ago.
Ms Owers called on the Government to urgently address the "fundamentally unsafe state" of Brook House, which is run by private company G4S.
In the six months leading up to the inspector's visit, detainees and staff reported 105 assaults, the majority against immigration guards.
Nearly half of immigrants held in Brook said that they had been victimised by other detainees and 37 per cent said they had been insulted or assaulted by a member of staff.
In two incidents, guards were found to have "illegitimately" used their shields against immigrants. In one case, guards used force against a detainee who had urinated through the door of his cell. One of the officers said in his statement: "I entered first with the shield. 'A' was standing up by the table and I hit him with the shield."
But Dame Owers said that many of the guards lacked the confidence and experience to deal with violence and bullying. "Our surveys, interviews and observations all evidenced a degree of despair amongst detainees about safety at Brook House which we have rarely encountered. Bullying and violence were serious problems and - unusually for the immigration detention estate – drugs were a serious problem."
She added: "Many detainees were ex-prisoners and a number compared their experience in Brook House negatively to that in prison. There had been significant staff turnover, particularly following an outbreak of serious disorder the previous summer. While many staff tried hard to maintain order and control, many felt embattled and some lacked the confidence to manage bad behaviour. A number of staff reported feeling unsupported by managers, and detainees claimed that some staff were bullied by more difficult detainees."
Brook House, the latest addition to the UK Border Agency removals estate, was opened on 18 March 2009. It is supposed to provide short term accommodation for 426 males.
But a fifth of detainees had been detained for more than six months and four were found to be children. In the three worst cases, adults had been held for more than three years solely under immigration powers.
Dame Owers said: "The challenge at Brook House was significantly compounded by poor design, which built in boredom by providing too little purposeful activity on the erroneous assumption that detainees would only be staying a few days."
David Wood, the strategic director for criminality and detention for the UK Border Agency, said: "We are extremely disappointed with this report, but accept its broad conclusions. That is why we have acted so swiftly to implement the vast majority of the improvements recommended. Since the inspection, we have introduced an anti-bullying policy and additional support for staff, including designated mentors.
"We are also developing a comprehensive drugs strategy for the estate to supplement the intelligence-led approach we have to preventing drugs coming in and being used in the centre. The vast majority of detainees in Brook House have committed very serious crimes, including drugs, sex and violent offences."