Two barge-loads of the mineral bauxite were allegedly dumped in the sea in the hours after a giant bulk carrier stranded in Solomon Islands.
The loader, Solomon Trader, has been stranded on a reef for a month, and has leaked about 100 tonnes of oil into a world heritage marine reserve.
The Solomon Star newspaper is reporting that the night the ship was cast adrift and struck the reef, two barges were sent out to try and rescue it.
But they themselves got into trouble near the reef and they unloaded the bauxite into the world heritage area, according to the the newspaper.
That's according to the accounts of several villagers along the Rennell coast, who witnessed the dumping.
They said it discoloured the water, unleashed a noxious odour, and killed fish.
Within days oil from the vessel started to leak into the water too.
Efforts to pump the remaining 600 tonnes of oil from the ship continue.