Major cracks have reportedly appeared in the hull of a cargo ship leaking oil in Mauritius.
More than 1,000 tonnes of fuel has already seeped from the bulk carrier MV Wakashio into the sea off south-east Mauritius, polluting the coral reefs, white-sand beaches and lagoons that attract tourists from around the world.
Despite bad weather, Prime Minister Pravind Jugnauth said 500 tonnes had been safely pumped out on Monday.
But he warned the country was preparing for the "worst-case scenario".
Locals on the island have questioned why more was not done to avert disaster when the ship first ran aground on 25 July.
Since the weekend, volunteers have been collecting straw from fields and filling sacks to make barriers against the oil.
Others have made their own tubes with tights and hair to add to the effort, and some have been cleaning up the island's beaches.
Japan and France have both said they will help with the operation but campaigners say that is not enough and have called for a full-scale coordinated international response.
The MV Wakashio ran aground at Pointe d'Esny, a known sanctuary for rare wildlife. The area also contains wetlands designated as a site of international importance by the Ramsar convention on wetlands.
Happy Khamule from Greenpeace Africa warned that "thousands" of animal species were "at risk of drowning in a sea of pollution, with dire consequences for Mauritius' economy, food security and health".
Mitsui OSK Lines, which operates the vessel owned by another Japanese company, promised on Sunday to “make all-out efforts to resolve the case”.
At a news conference, Akihiko Ono, executive vice-president of Mitsui OSK Lines "profusely" apologised for the spill and for "the great trouble we have caused".
Police in Mauritius say they have been granted a search warrant, allowing them to board the vessel take away items of interest such as the ship's log book in order to help with an investigation.