An estimated 250 people have marched in Noumea in protest at the authorities' silence over recent oil pollution in New Caledonia.
At the end of November, black globules began washing up on the shores of the Loyalty Islands and the main island's east coast, apparently from a wrecked container ship off Mare.
An alert was issued along with local fishing and swimming bans.
Reports say the demonstrators want to be properly briefed about what happened and what will be done to remedy the situation.
At the weekend, the visiting French prime minister Edouard Philippe was also challenged over the spillage.
The ship Kea Trader broke up last month after months of unsuccessful efforts to refloat it.
Last week, the French High Commissioner Thierry Lataste said the ship owners assumed responsibility and would pay for the clean-up effort despite there not being any official confirmation about the source of the pollution.
The Kea Trader ran on the Durand Reef in July in as yet unexplained circumstances.