Serious allegations of conspiracy and corruption made against the New Zealand police by a former officer have seen his personal grievance case escalated to the Employment Court.

Senior constable Sean Ramkissoon said he was "unfairly" demoted from his sergeant's position in Opotiki and was treated poorly when he became unwell with a stress-related illness in July 2009.

Among his complaints were allegations that high-ranking police staff wrongly asserted he was not genuinely sick and pressured him to return to frontline duties before he was ready.

The former officer, who is now living overseas, has taken two personal grievances against the police and is seeking reinstatement to the force.

In a just-released ruling, the Employment Relations Authority said it had agreed to a request from the Police Commissioner for the case to be heard by the higher Employment Court, because the matter was of public interest due to the allegations made.

"They comprise allegations of conspiracy, corruption, dishonesty, collusion, oppression and harassment," the  ERA ruling said.

"There was no apparent foundation for some of them, but many have been made because Mr Ramkissoon believes the aftermath of another earlier matter in which he had an involvement influenced the actions he now complains of."

The ERA said Ramkissoon was dismissed from the police due to ill health in June 2011.

Prior to that he had been appointed to a sergeant's position in Opotiki, which was cancelled following a review lodged by the human resources department in 2009.

Ramkissoon said that was outside the department's jurisdiction. He also complained that when the position was readvertised, it excluded him by including a new requirement regarding residence, though he was otherwise qualified.

Following that incident, Ramkissoon became ill and was placed on special duties, when the questions about the validity of his illness allegedly arose.

He was then "medically disengaged", and raised a grievance on the ground of unjustified dismissal.

The presiding ERA member decided the case could be heard by the court, mainly due to issues concerning the scope of the power the human resources department had in beginning the review of Ramkissoon's position.

- © Fairfax NZ News