More than 100 tons of petrol and kerosene spilled into a Vietnamese waterway after two vessels collided last week, an official said Saturday, in the latest case of growing industrial pollution.

About 40,000 liters of petrol, 70,000 liters of kerosene, and a load of construction material contaminated the Vam Co Dong river south of Ho Chi Minh City after the accident, a local official said.

"We recovered several dozen liters of fuel," Nguyen Van Thuan, head of the Long An provincial Natural Resources and Environment Department, told AFP. "The cause of the collision is still unknown."

Environmental experts and the country's communist government have raised concern about the heavy pollution of rivers by industrial parks arising from former rice fields amid the country's 8.5 percent annual economic growth.

Contamination of the Saigon River, which flows through the industrial hub and main port of Ho Chi Minh City, "has risen alarmingly due to massive industrial and domestic discharges," the Thanh Nien daily reported this week.

Tests by HCMC University of Technology and Japanese researchers have shown heavy metal and bacterial pollution far above safe levels, the newspaper said.

Bui Thanh Giang, head of a utility that treats the river water for Ho Chi Minh City's water supply, said industrial parks and residential areas pumped untreated effluent into the waterway and its tributaries, the report said.

Vietnam's Ministry of Natural Resources and the Environment, in its first ever river pollution report last year, highlighted industrial and medical waste pollution in the northern Cau and Nhue-Day and the southern Dong Nai rivers.