The Sri Lankan navy on Wednesday said that it is getting ready to deal with a possible oil spill after the fire-stricken Singapore-flagged cargo ship laden with chemicals sank in the outer Colombo Harbour after an unsuccessful bid to tow the vessel to the port.

Water submerged the MV X-Press Pearl’s stern a day after firefighters from Sri Lanka and India climbed onto the vessel and extinguished a blaze that had been burning for 12 days.

The development has led to grave environmental concerns as the container ship still has several hundred tonnes of oil in its fuel tanks.

“We are actually getting ready for an oil spill that could happen in the next few days,” Captain Indika de Silva, the navy spokesman said.

He said the salvors had got on board the ship at 4am on Wednesday morning and the action to tow it to the outer area had begun by 9am.

Experts were trying to tow the ship farther out to sea, some 9 nautical miles away from the Colombo port where it had been anchored since May 20, to prevent it sinking at the current position which would have caused severe pollution.

The order to tow the ship came from President Gotabaya Rajapaksa late on Tuesday.

“It could be towed only for a few hundred metres when it hit the sea bed,” he said, adding that the ship’s stern had settled on the bottom while the bow was floating.

De Silva said he was not sure if the fire which engulfed the ship 12 days ago had also spread to the bunker oil.

“We don’t know yet, but we are getting ready,” he said.

The Sri Lankan Navy, with assistance from the Indian coast guard, doused the flames after a strenuous effort, officials said.

The environment and marine ecological pollution is regarded as the worst the island had seen.

The ship’s cargo, comprising chemicals and nitric acid, were termed hazardous to marine ecology.

At least 8 containers had fallen in the sea when it was anchored and went up in flames some 9 nautical miles off Colombo port.

The authorities imposed a fishing ban in the area while the Central Environmental Authority and the Marine Environment Protection Authority began their investigations to make assessments of the damages to stake a legal claim for compensation from the ship’s owners.