Two Government entities face a competition investigation over the way they sell weather data to private competitors.
The Commerce Commission has initiated a probe into the National Institute of Water and Atmospheric Research (Niwa) and MetService under sections 27 and 36 of the Commerce Act.
A spokesman for the competition watchdog declined to give details of the investigation while it was under way.
However Philip Duncan, chief executive of Weatherwatch, a private company which provides weather forecasting services, said the commission had told him that it had opted to begin the investigation "after reviewing the recent quotes for observational data and rain radar data provided by MetService and Niwa to WeatherWatch".
Duncan has been accusing both Niwa and MetService of anti-competitive behaviour for years, claiming the entities restrict data and charge "astronomical" prices which are higher than similar entities anywhere in the world.
He first began complaining since around 2011 and has been urging the commission and politicians to act ever since.
News of the probe from the Commerce Commission was one of "relief", partly because he suspected that after he had been complaining for so long, people would have been doubting his claims.
"This backs up a lot of what we've been saying for a number of years," Duncan said.
A spokesman for MetService said the investigation related to a complaint by Weatherwatch about the terms upon which competitors could access data.
"We do not yet have any detailed information about the investigation, but MetService will fully co-operate with all investigations led by the Commerce Commission on this matter."
Niwa said it welcomed the investigation.