The scientist who developed the system for measuring the anti-bacterial properties in manuka honey has severed his ties with the organisation that administers it.
Research led by Professor Peter Molan of Waikato University found some manuka honey contains anti-bacterial properties that are now being used in products to aid immune response and wound healing.
Professor Molan developed a scale for measuring anti-bacterial properties known as the Unique Manuka Factor or UMF scale.
The Active Manuka Honey Association, or AMHA, is responsible for maintaining the UMF brand, and companies that produce Active Manuka Honey must be members of the association in order to use the brand.
Professor Molan has written to AMHA members saying he had decided to no longer have anything to do with the association or UMF.
He said he held the association's executive responsible for reaching that decision.
The Active Manuka Honey Association says it cannot comment because court proceedings are taking place, and it is under judge's orders not to talk on the matter.