Several soldiers were among the eight men hospitalised after taking a mystery drug in Palmerston North in the early hours of this morning.

Police were called to the group of men who were suffering effects from an unknown substance at 3.30.

The men were taken into custody before being taken to Palmerston North Hospital for treatment.

All eight have been treated and discharged.

It is not known what the substance was.

A New Zealand Defence Force spokeswoman says any charges laid before the courts will be at the discretion of the Police and the Force will be making no further comment.

Linton Military Camp is the largest New Zealand army base, located just south of Palmerston North

A source says the substance was thought to be N bomb, the illegal synthetic drug which is a powerful synthetic hallucinogen related to amphetamines.

Earlier this month, the newly emerged drug led to six people being treated in Christchurch Hospital.