Leaked messages show prison staff at a Welsh prison laughing at violent encounters with inmates and making fun of self-harm incidents.

In them, one staff member at privately run HMP Parc in Bridgend responded to a complaint about an inmate and said: “The prisoners need to be broken mentally and physically.”

It is understood the messages, seen by the BBC, were shared on social media last summer.

G4S, which runs HMP Parc, said it had a “zero tolerance” approach to staff behaviour that fell short of its standards.

In the messages, one exchange about an inmate said: “XXX opened the door and they smashed him into the shower lol.”

A response to the message said: “Good! I hope they hurt him too.”

A separate exchange used an expletive to describe punching an inmate “after he bit me so there’s some closure”, along with a laughing emoji.

Other messages included jokes about someone who was said to be at risk of taking their life and another offender who was seriously self-harming.

Some 17 inmates are known to have died at Parc in 2024 – more than any other prison.

In a letter to the Justice and Home Affairs Committee in October 2024, Prisons Minister James Timpson said the prison service’s corruption unit was looking at the prison.

Last September, four of the prison’s custody officers were arrested on suspicion of assault and misconduct in public office following reports of a series of incidents at HMP Parc.

All four have been released without charge, South Wales Police told the BBC.

The force said an additional arrest phase took place in January 2025 following the four arrests.

A 36-year-old man from Llanelli has been released under investigation, while a 35-year-old man from Bridgend, 40-year-old man from Swansea, 38-year-old man from Barry, 50-year-old man from Taibach and a 23-year-old woman from Cardiff have all been bailed for further inquiries until the end of April 2025.

South Wales Police Det Ch Insp Dean Taylor said: “The investigation remains ongoing, and officers are continuing to work closely with G4S.”

A G4S spokesperson said: “Of the four individuals who were arrested and released without charge by South Wales Police, three have been dismissed from the company and one remains suspended from duty pending the outcome of a disciplinary process.

“The vast majority of our staff are hardworking and honest. We are absolutely committed to rooting out any wrongdoing.”

In response to the messages, G4S added: “Our staff are expected to treat everyone with dignity and respect and we have a zero tolerance approach to dealing with any staff behaviour that falls short of our standards.”