Dozens of prison officers are joining a picket line outside HMP Liverpool at the start of their second day of unofficial strike action.
Up to 200 of them walked out on Tuesday, amid claims of bullying and harassment by their supervisors, reports the BBC.
The Prison Service has condemned the action as “wrong and unsafe”.
At the moment, the prison is being run by 20 officers and 30 managers, and police patrols outside the building have been increased.
The Prison Officers’ Association (POA) said that prison staff had grown tired of being “managed by fear”.
A POA spokesman told BBC News: “We have had a management at Liverpool prison that has constantly bullied staff.
“It works with a two-tier system. Allegations of a manager being a bully are always pushed under the carpet, but prison officers are finding themselves in trouble over a whole range of things.
“Staff have been moved, dismissed by a wrong and unjust management.”
The POA said it wanted to have “meaningful talks” with the Prison Service but would continue its strike.