The Commerce Commission says it is investigating allegations of price-fixing within the pharmaceutical industry.
The allegations follow changes to the Community Pharmacy Services Agreement in July 2012 that prohibited pharmacies from discounting prescriptions.
The new clauses in the agreement were disputed by Linwood Community Pharmacy owner Joe Tiller who wanted to continue offering discounts.
In response, the Commerce Commission removed the clauses in December 2012, saying that they reduced market competition.
The commission is now investigating whether the initial decision by DHB Shared Services to add the clauses was the result of attempted price-fixing.
It says it is investigating several organisations that made submissions supporting the clauses.
The commission would not say who made the allegations or when the investigation is likely to be completed.