The captain of the ship that spilled tons of oil onto the coast of Mauritius was arrested on Tuesday, according to local media.

Sunil Kumar Nandeshwar and his second mate Tilak ratna Suboda were charged with endangering safe navigation. They are being held in prison until August 25, when they will reappear in court.

The Japanese vessel, Wakashio, ran aground on a coral reef, Pointe d’Esny, on 25 July, near two marine ecosystems.

Strong waves caused the ship to start leaking oil on August 6.

The vessel later split in two over the weekend. The rear part is stranded on the reef with about 90 tonnes of fuel onboard.

The ship was carrying 4,000 tonnes of fuel oil. 1,000 tonnes spilled into the waters and most of the remaining fuel oil has been recovered.

But environmental groups warn the damage to the coral reefs could be irreversible.

Mauritius has said it will seek compensation from the owner of the ship, Japanese firm Nagashiki Shipping.

A team of experts from Japan are arriving in Mauritius on Wednesday to help with the clean-up.

The Mauritius government has also come under fire to explain why immediate action wasn’t taken to empty the ship of its fuel before it began to leak.

Prime Minister Pravind Jugnauth earlier blamed bad weather for the slow response.