Authorities in Mauritius have arrested the Indian captain and chief officer of the capesize bulker responsible for what is being called the country's worst-ever environmental disaster.

Sunil Kumar Nandeshwar, the 58-year-old Indian man in charge of the 203,000-dwt Wakashio (built 1997), has been charged with endangering safe navigation, the BBC reported citing police.

Owner Nagashiki Shipping confirmed the master and chief officer had been arrested by the local authority on 18 August.

The Japanese-owned, Panama-flagged Wakashio ran aground on the Pointe d'Esny coral reef on 25 July, spilling a thousand tonnes of fuel oil.

Court appearance

The BBC said Nandeshwar had made an appearance in court to hear the charges and will be held by police until 25 August. Reuters reported a second crew member had been arrested, as well.

"We have arrested the captain of the vessel and another member of the crew," Mauritian inspector Siva Coothen told the newswire.

"After having been heard by the court they have been denied bail and are still in detention."

The other crew member's charges are not known at this time.

The Wakashio had a crew of 20 — three Indian officers, plus 16 Filipinos and one Sri Lankan.

It was managed by Nagashiki Shipping and was chartered by Mitsui OSK Lines.

MOL said it is "doing everything possible" to support the efforts of Nagashiki Shipping to mitigate the effects of the spill.

A team of specialists continue to work on recovering the remaining oil from the sea and coastal areas in order to minimise the impact to the environment, it added.

MOL has sent a team of six employees that arrived in Mauritius on 12 August. It has also sent equipment to help recover oil from the sea and coastline. This is due to get there on 21 August.

A second team of staff will be travelling to Mauritius later in the month.

Investigations

According to unconfirmed media reports, the ship changed its route in order to secure wireless internet during a birthday celebration for one of the crew members.

Reuters cited an official, who said the ship was told by the coastguard that its course was dangerous but refused to change. MOL said the ship was 20 miles off course when the grounding occurred.

The incident spilt 1,000 tonnes of the roughly 4,000 tonnes of fuel oil on board over a sensitive ecological area. The remainder was removed from the ship.

Over the weekend, it split in two and on Tuesday, the bow section was being towed from the scene.

Japan has sent a team of oil spill experts to aid in the clean-up and plans to send more, with the delegation focusing on both near-term and log-term remediation, Reuters reported.