Authorities in Sri Lanka were trying to head off a potential environmental disaster Thursday as a fire-damaged container ship that had been carrying chemicals was sinking off of the country’s main port.

The Singapore-flagged MV X-Press Pearl started sinking Wednesday, a day after authorities extinguished the fire that raged on the vessel for 12 days. Efforts to tow the ship into deeper waters away from the port in Colombo failed after the ship’s stern became submerged and rested on the seabed.

The ship’s aft portion is sitting on the seabed at a depth of about 21 meters, and the forward section “continues to settle down slowly,” according to a Thursday statement on the company’s incident website. There are “no reports of oil pollution” at the site of the shipwreck as of 7 a.m. Sri Lankan time, according to the statement.

The ship’s operators X-Press Feeders have said the fire destroyed most of the ship’s cargo, which included 25 tons of nitric acid and other chemicals. But there are fears that the remaining chemicals, as well as hundreds of tons of oil from the vessel’s fuel tanks, could leak into the sea if it sinks.

Such a disaster could devastate marine life and further pollute the island nation’s famed beaches. The disaster has already caused debris — including several tons of plastic pellets used to make plastic bags — to wash ashore.

The government already has banned fishing along about 80 kilometers (50 miles) of coastline.

The ship operator said Thursday that the ship’s stern was resting on the seabed about 21 meters (70 feet) below the surface and the ship’s bow was “settling down slowly.” The company said salvage experts were remaining with the vessel “to monitor the ship’s condition and oil pollution.”

The company said its experts were coordinating with Sri Lanka’s navy to deal with an oil spill or other pollution.

Sri Lanka navy spokesman Indika de Silva said the navy and coast guard were preparing for an oil spill with assistance from neighboring India. India has sent three ships to help, including one specifically equipped to deal with marine pollution.

Meanwhile, the head of the salvors has been instructed to carry out rescue operations without any oil spill or environmental damage, said the Chairman of the Maritime Environmental Protection Authority (MEPA), Attorney-at-Law Dharshani Lahadapura.

A team of Sri Lanka Navy divers is currently deployed to inspect for any oil spills from the fire-ravaged ship.

Environmentalist Ajantha Perera said there was the potential for “a terrible environmental disaster” as hazardous goods, chemicals, and oil could be released into the water and destroy marine ecological systems.

Charitha Pattiaratchi, a professor of oceanography at the University of Western Australia, said as many as 3 billion tiny plastic pellets had already been released into the sea and were washing up on beaches. He said the pellets, known as nurdles, “will persist in the marine environment forever as they are not biodegradable.”

The fire erupted on May 20 when the ship, carrying 1,486 containers including 25 tonnes of nitric acid, other chemicals, and cosmetics, was anchored about 9.5 nautical miles (18 kilometers) northwest of Colombo and waiting to enter the port.

The navy believes the blaze was caused by the vessel’s chemical cargo, which was loaded at the port of Hazira, India, on May 15.

Sri Lankan police are probing the fire, and a court in Colombo on Tuesday banned the captain, the engineer, and the assistant engineer from leaving the country. The government has said it will take legal action against the owners of the ship to claim compensation.

Sri Lanka’s Environment Minister Mahinda Amaraweera said “it wouldn’t be an easy task to calculate the damage caused to our environment.”

He told the media late Wednesday that an investigation was underway to determine what went wrong and whether the shipping company was responsible.

“If this disaster happened due to negligence, then those responsible should be punished,” he said.

-With inputs from agencies