The Cook Islands Opposition Democratic Party says the dumping of Jacqui Evans from the Marae Moana is appalling.
The party leader, Tina Browne, said by removing the world-renowned environmentalist the government has a reached an all-time low.
She said it is completely unacceptable for the government to do this to a highly qualified, passionate Cook Islander who has dedicated most of her life to the protection of the ocean.
Ms Brown said she is aware that Ms Evans didn't back the government on its plans to ignore the regional call for a 10-year moratorium on seabed mining.
She said the government instead wants to fast pace mining within the Cook Islands EEZ.
The Cook Islands Government has not yet explained why it took the action it did.