The political party, Caledonia Together, has questioned the apparent inaction of the authorities of the southern province in dealing with a rupture of an effluent pipe of the Vale nickel plant.
The plant suspended operations last week after it became public that the pipe through a lagoon in a World Heritage site was broken.
The party says the authorities are tasked to inspect the 26 kilometre pipe every six months, but it has emerged that this has not been done for two and a half years.
The Vale leadership has said the incident has had no impact on the environment.
It had to report to the southern province about the pipe issue.
Its outcome is not known yet and it remains unclear when the six-billion US dollar plant will resume operations.