A total of 18 women working at a north Wales prison have been sacked or resigned after crossing relationship boundaries with inmates.
Three female guards at HMP Berwyn in Wrexham have been jailed for having relationships with prisoners.
But a Freedom of Information request showed a wider problem at the UK’s biggest male prison.
Anti-corruption training has been given to more than 500 staff in the past 18 months, HM Prison Service said.
In December, Jennifer Gavan, 27, of Llay, Wrexham, became the third staff member to be jailed for having a relationship with a prisoner, following Ayshea Gunn, then 27, and Emily Watson, who was 26 at the time.
The FOI subsequently found 18 women were suspected of, or had had, inappropriate relationships with inmates at the 2,000 capacity facility.
Some were operational staff at the prison and others were working there from partner organisations in areas such as rehabilitation.
Four operational staff were sacked and two from partner groups.
Three staff members resigned while a further nine from partnerships also resigned.
Staff ‘not above the law’
HM Prison Service announced the enhanced training after Gavan was sentenced last year.
It said in a statement: “Our frontline staff are nothing short of heroes – undergoing an extremely tough and demanding job day-in day-out to get criminals back on the straight and narrow and keep our streets safe.
“It is for their sake we will never tolerate those few officers who think they are above the law.
“That’s why our newly bolstered Counter Corruption Team is working around the clock to root out and clamp down on those who undermine our exemplary service with their dangerous behaviour and ensure they face the strongest possible consequences for their crimes.”