The Ministry of Public Security's environment department (C49) has asked police and authorities in the northern province of Lao Cai to cooperate in investigating the causes of pollution found in the Red River.
The investigation was announced about a week after the Vietnam Environment Administration concluded that the upstream areas of the 1,150-kilometer river in Lao Cai and Yen Bai provinces were badly contaminated with iron, lead and organic substances.
According to C49, the pollution of the river, which originates in China's Yunnan Province, was caused most likely by untreated waste discharged from factories in Vietnam as well as China.
A senior C49 official told Thanh Nien on the condition of anonymity that the department and provincial agencies would review activities of all local businesses to detect those polluting the river.
In case the pollution was not caused by Vietnam, the two countries, including adjacent localities on the border, need to join hands to figure out solutions, he said.
However, the department has said that further tests on the river's water samples are needed before they come to precise conclusions.
Last week the environment administration, which works under the Ministry of Natural Resources and Environment, had announced its tests' findings after local press reports mentioned that the river's section in Lao Cai Province smelled strange and had films of red mud on its surface.