The captain of the ship that spilled hundreds of tonnes of oil off the coast of Mauritius has been arrested.
Sunil Kumar Nandeshwar, a 58-year-old Indian man, was charged with endangering safe navigation, police said. He has not yet commented.
The MV Wakashio ran aground on a coral reef, Pointe d'Esny, on 25 July while carrying 4,000 tonnes of fuel oil, causing an ecological emergency.
Pointe d'Esny is a sanctuary for rare wildlife.
Mr Nandeshwar made an appearance in the district court in the capital Port Louis to hear the charges.
He will be held in a police cell until he returns to court on 25 August.
Police said crew members questioned as part of their investigation informed them there had been a birthday party on the ship the day it ran aground.
Another theory being investigated is that the ship navigated close to the shore in order to pick up WiFi signal, the BBC's Yasine Mohabuth, in Port Louis, reports.
The Japanese-owned MV Wakashio has already leaked about 1,000 tonnes of fuel oil into the uniquely biodiversity-rich marine ecosystem.
The ship split in half over the weekend and the bow of the ship is being towed away from the reef.
But the rear part remains stranded on the reef with about 90 tonnes of the fuel believed to be on board.
Rough seas have made it too risky to remove the remaining oil from the ship, the national crisis committee has said.
"Due to the adverse weather conditions, it is still risky to remove the remaining small amount of residual oil in the engine room", the National Crisis Management Committee said on Monday evening, adding that "oil pumping operations should resume as soon as the weather permits."
Mauritius has said it will seek compensation for the leak from "the owner and the insurer" and Japanese firm Nagashiki Shipping has pledged to respond to requests for compensation.
A team of experts from Japan are arriving in Mauritius on Wednesday to help with the clean-up, Japan's foreign ministry has said.
Earlier this month, Mauritian Prime Minister Pravind Jugnauth declared a state of emergency and appealed for international help.
Volunteers took the matter into their own hands, filling sacks with straw to make barriers against the oil - despite orders from the government to leave the operation to the authorities.
On Monday, around 416 cubic meters of the homemade barriers - called booms - were collected and found to be saturated with oil, our correspondent reports.
The amount of oil spilled is relatively low compared with the big spills the world has seen in the past.
However, unlike most previous offshore spills, this has taken place near two environmentally protected marine ecosystems and the Blue Bay Marine Park reserve, which is a wetland of international importance.