Ministers are being urged to reverse plans to issue prison officers with a synthetic pepper spray, known as Pava, following a trial.
From next year, canisters will be issued to staff in publicly run prisons for men, in a bid to reduce violence.
The Prison Reform Trust (PRT) says its own analysis of the six-month trial in four prisons showed the spray was often used “unsafely and inappropriately”.
Ministers have said trials of the pepper spray were “successful”.
The official report gives details of 50 cases where the chemical incapacitant was deployed.
The trials took place in four prisons: Hull, Preston, Risley and Wealstun in 2017 and 2018.
Officers were trained and issued with Pava, which was intended to be used as a last resort as a personal protection tool “to prevent harm to self or others”.
In the guidance, they were told to deploy it only when other techniques were not possible, had already failed or were considered unsafe or insufficient.
In a letter to the PRT in November, prisons minister Rory Stewart says the spray is intended for use “in exceptional circumstances where a member of staff is faced with serious violence or the perceived threat of serious violence”.
However, the campaign group says its analysis, carried out by an experienced former prison governor, shows that in almost two-thirds of these incidents, officers might have contravened the guidance.
“In fact, the use of Pava very rapidly became a routine part of how routine incidents were dealt with,” says the PRT.
Incidents of inappropriate use in the official report include:
- use against a prisoner who was harming himself
- an inmate with mental health problems sprayed three times in 10 minutes, including at point-blank range through a flap in his cell door
- an officer spraying the wrong prisoner and a colleague attempting to intervene in a fight
- use of the spray on a prisoner who had jumped on to the safety netting between the floors