PORT LOUIS (Mauritius) • Police in Mauritius yesterday prepared to board a grounded ship leaking tonnes of oil into its crystal clear waters, as clean-up crews confronted a growing ecological disaster on the archipelago's pristine shores.

The Japanese-owned bulk carrier MV Wakashio has been seeping fuel into a protected marine park boasting unspoiled coral reefs, mangrove forests and endangered species, prompting Prime Minister Pravind Jugnauth to declare an environmental emergency and appeal for international help.

Attempts to stabilise the stricken vessel, which ran aground on July 25 but started leaking oil only last week, and pump 4,000 tonnes of fuel from its hold have failed. The local authorities fear rough seas could further rupture the tanker.

Hundreds of volunteers, many smeared head to toe in black sludge, are marshalling along the coastline, stringing together makeshift cordons in a desperate attempt to hold back the oily tide.

But already, thick muck has inundated the island nation's unspoiled lagoons, marine habitats and white sand beaches, causing unprecedented damage to the fragile coastal ecosystem upon which Mauritius and its economy relies.

Police said yesterday they would execute a search warrant granted by a Mauritius court to board the Wakashio and seize items of interest, including the ship's log book and communication exchanges.

The vessel's captain, a 58-year-old Indian national, will accompany officers on the search.

Twenty crew members who had earlier evacuated safely from the Japanese-owned but Panamanian-flagged ship when it ran aground are under surveillance.

The ship's operator yesterday apologised for the spill.

"We apologise profusely and deeply for the great trouble we have caused," Mr Akihiko Ono, executive vice-president of Mitsui OSK Lines, said in Tokyo. He added that the firm would "do everything in its power to resolve the issue".

REUTERS, AGENCE FRANCE-PRESSE