Maori Party co-leader Pita Sharples says the party is fundamentally opposed to probation periods for new employees.
The Government has signalled it will extend a 90-day trial to all workplaces as part of a package of employment law changes.
Dr Sharples says his party opposed the fire-at-will policy in 2008 when it only applied only to small workplaces, and he does not want to see it extended.
He told Waatea News it is based on an unfair idea and the Maori Party would never support it.
Dr Sharples said the Government has failed to prove that the existing legislation has created job opportunities for young Maori.