The master and chief officer of a Japanese bulk carrier, which caused a pollution disaster off Mauritius, have both been sentenced to 20 months in prison and fined for endangering the safe operation of the ship.

Master Sunil Kumar Nandeshwar and chief officer Hitihanillage Subhoda Janendra were in command of the 203,000-dwt Wakashio (built 2007) when it grounded off Mauritius in July 2020.

More than 1,000 tons of fuel oil leaked from the vessel causing the country's worst ever marine pollution disaster.

Prior to sentencing the men had pleaded guilty to breaking Mauritius' Merchant Shipping Act. Both men are expected to be released shortly in consideration of the 16 months they have already been held in custody.

Nandeshwar admitted to drinking moderately at a birthday party, which was held on the ship at the time of the grounding.

In a statement the vessel's owner, Japan's Nagashiki Shipping, said: "We sincerely apologise for the inconvenience caused to all concerned parties. We take this decision seriously and will continue to thoroughly implement the recurrence prevention measures published in December last year."

The company said it would seek to comply with laws and regulations in its business activities. It said it wanted to establish higher ethical standards and further improve its safety and quality standards.

Both Nagashiki and the vessel's charterer Mitsui OSK Lines earlier reported in their safety investigations into the disaster that the ship had sailed too close to the coastline as crew searched for a mobile phone connection.

There is an ongoing wreck removal operation to remove the stern section of the Wakashio, which remains aground off the Mauritius coast.

"We take our obligations in relation to this incident seriously. We will continue to cooperate with local authorities, and the other parties involved, to safely remove the wreckage as soon as possible. We will continue to support local society and restore the environment," Nagashiki said.

The Wakashio ran aground at a rare wildlife sanctuary at Pointe d'Esny and badly damaged the local coral reef. The area is a designated site of international importance under the Ramsar convention on wetlands.