He was responding to questions from Rabaul MP Allan Marat in the morning session of Parliament.
Marat asked if a policy, which will give a single company monopoly, will strain ties with Australia.
PNG imports K700 million of rice annually, and Australian company Trukai is the major importer.
Minister Maru, in response, said he had already sought advice from WTO in-country and legal advice from the State Solicitor’s Office.
"Such a policy will be in serious breach of our obligation as a member of the World Trade Organization," Maru warned.