The Corrections Department is being urged to investigate whether inmates at Auckland prison at Paremoremo are being forced to get tattoos.
Lawyer Heeni Phillips says one of her clients asked to move to a different wing of the jail because he feared gang members would tattoo him using a dirty needle.
Ms Phillips, who is the secretary of the Howard League for Penal Reform, says prisoners could be exposed to hepatitis.
Auckland prison Neil Beales says an investigation will be held if there's a formal complaint by an inmate.
But former head of the prison service Kim Workman says that is not easy for inmates to do, because they fear reprisals.