The suspension of another guard from Rimutaka Prison has brought the number of officers suspended in full pay from the Upper Hutt facility to six of the approximately 440 staff.
The latest suspension is reported to involve a female guard accused of having a relationship with a male prisoner.
The Corrections Department will not talk to Radio New Zealand about the allegations, but it has confirmed in a statement that a guard was suspended in late July.
The statement says an investigation was launched as soon as the department became aware of the accusations, but it says it will not comment further as it may jeopardise possible legal action.
Having a sexual or financial relationship with a person for whom an employee has custodial or counselling responsibility is listed as "serious misconduct" in the department's code of conduct.
There have been numerous incidents, both proven and alleged, at Rimutaka Prison in recent years. They range from serious assaults and drug offences to corruption and smuggling contraband, and involve both guards and inmates.