Severe pollution in southern Vietnam has caused water in a river in the Mekong Delta to turn black, killing fish and other marine life.

Residents living near the Cai Lon River in Hau Giang Province claim that a sugar factory located by the river has been discharging untreated effluent, VN Express reported.

Water in the river has turned black as a result and is also spreading foul smell.

Local authorities said they have taken samples of the polluted water to determine the cause and will take action accordingly.

Long My Town resident Pham Thi Thuy Linh, 35, said the water has been pitch black for 10 days and is only getting worse. Almost all of the fish, shrimp and frogs being farmed by nearby households had been killed by the polluted water, he said.

The Cai Lon River is the key source of water in Long My Town. A water treatment plant in the neighborhood uses about 4,000 cubic meters from the river to provide water for 6,000 families in the town.

However, the river has become so polluted that the plant is now extracting water from artesian basins under the ground instead.