It is understood the substance is a drug.
A spokesperson for the defence force confirmed they were investigating the incident which took place on Saturday.
“The five personnel have been stood down from their normal duties while the investigation progresses,” they said.
“This matter has not effected the NZDF's humanitarian support operation in Fiji.”
Defence force staff are currently in Fiji along with the HMS Canterbury assisting with the recovery of Tropical Cyclone Winston.
