Colombo, May 25 (IANS): Sri Lankan authorities on Tuesday rescued 25 foreign crew members onboard a cargo ship which was engulfed in flames off the Colombo Harbour, while the Navy said an explosion was heard within the vessel earlier in the day.

The Singapore-flagged container ship, X-PRESS PEARL, was carrying 1,486 containers with 25 tonnes of nitric acid and several other chemicals and cosmetics from the port of Hazira, India, on May 15, according to the Navy.

The vessel sent out a distress call while being close to the Colombo Port on May 20, and soon caught fire, reports Xinhua news agency.

The Sri Lankan Navy dispatched vessels to bring the fire under control.

By Tuesday morning, eight cargo containers had fallen into the sea and the vessel was reported to be unstable, the Marine Environmental Protection Authority (MEPA) said.

The Sri Lanka Navy said it had rescued 25 crew members from the cargo ship.

Two injured Indians among the rescued had been hospitalised for treatment, according to the Navy.

The distressed container ship had a crew who are Philippine, Chinese, Indian and Russian nationals.

The Sri Lanka Air Force (SLAF) said it had deployed Bell-212 helicopters to drop dry chemical powder on the X-Press Pearl to douse the fire.

While these operations were ongoing amid inclement weather, the MEPA urged citizens in capital Colombo to avoid going to the beaches and touching any floating objects in the water as they might be chemicals from the burning fire.

The MEPA has launched a probe to assess if there has been any environmental destruction due to the fire.