[Manus Governor] Mr Benjamin was concerned by the recent suicide attempts, the damage to Manus's reputation as a safe and welcoming place, and the social problems he said the project had brought.
He wants the Australian Government to remove the remaining men.
"The PNG Government can't do much and [Manus] can't do much. If we allow them to stay here, we will get even more problems, nothing will be solved," he said.
"We have to solve this problem and the only way to solve this problem is for Australia to act."
The Governor said he will be raising the issue with the country's new Prime Minister, James Marape.
Mr Benjamin was a key backer of Mr Marape, who took office less than a fortnight ago.