(CNN) -- The captain and second officer of a container ship that ran aground last year resulting in New Zealand's worst maritime environmental disaster, pleaded guilty Wednesday to a range of charges.
At a court in Tauranga in northeastern New Zealand, the two men pleaded guilty to ten of eleven charges brought by Maritime New Zealand, which included operating a vessel in a dangerous manner, discharging harmful substances and perverting the course of justice by altering ship documents.
The identities of the men, both Filipinos, have been suppressed.
Currently remanded on bail, they will be sentenced on May 25, according to a statement from Maritime New Zealand.
Willfully perverting justice carries the heaviest maximum penalty of the charges, with seven years of imprisonment.
The cargo vessel, Rena, hit a reef off Tauranga in clear conditions on October 5. At least 350 tonnes of fuel oil spewed into the sea, killing thousands of sea birds and contaminating the beaches of Tauranga's Bay of Plenty.
Efforts to clean tainted beaches and salvage the containers and debris from the stricken ship are still underway.