The identity of a police officer charged with assaulting five prisoners, including one who lost a testicle as a result, can now be revealed as Martin James Folan, 45, a sergeant based at Henderson in West Auckland.

A suppression order previously prevented the publication of Folan's name, rank and the station at which he worked.

However, that order lapsed when he appeared in the North Shore District Court last week.

Folan allegedly assaulted the five men over a three-month period. He is accused of kneeing one of the men so hard in the groin that the man had to get a testicle surgically removed.

Folan is one of four Henderson-based officers under investigation for assault.

Constables Gareth Needham and Alan Douglas will appear in court this month and another is being investigated for allegedly assaulting members of the public while on duty.