A nationwide crackdown has begun on sand and gravel extraction which is affecting the flow of rivers, their dyke systems and agricultural land.

The Waterway Police Department has been ordered to check all sand extraction enterprises and ships to ensure they follow the regulations on mineral extraction, inland waterway traffic safety and environmental protection.

There were about 50 illegal sand and gravel extraction spots across the Red (Hong), Day and Ca Lo rivers, which had a total length of 180km, the Hanoi Flood and Storm Control and Dike Management Department reported.

About 30 hot spots were on the 124km Red River alone. Owners of the exploiting operations, most of whom come from Bac Ninh, Hai Duong and Phu Tho provinces and Hai Phong City , preferred the locations because there was a large amount of black sand which returned a good profit.

It often took a 600-tonne boat about two or three hours to suck up and pump sand.

Every day, dozens of boats take sand across the Ca Lo River, which runs through Soc Son District's Xuan Thu, Xuan Lai and Yen Phu communes.

A boat owner said that his boat took up about 120cu.m of sand a day which was sold at 40,000 VND (2 USD) per cubic metre.

Deputy head of the city's Waterways Police Division Duong Van Binh said sand exploiters had sophisticated tricks, thus the waterways police, with only a small force, found it difficult to catch them red-handed.

Sand extractors often worked in the evening or at night to evade police, he said.

When detected, boat owners were ready to leave their vessels and jump into the river, said Binh.

Illegal extraction happened not only in Hanoi , but also in many different provinces, such as Thai Nguyen, Bac Giang and Vinh Phuc. It caused erosion along the Pho Day River in Vinh Phuc province and damaged the province's dyke system.

Authorities in Xuan Thu, Xuan Lai, Vong La and Hai Boi communes in Hanoi said they had shown the regulations to the extractors many times, and even fined them or stopped them working, but they came back after two or three days.

The commune authorities did not have the competence to crack down on boats violating regulations.

Duong Manh Hung, a lawyer from the Hanoi Bar Association, said the illegal extractors could be prosecuted under the law.

Meanwhile, director of the Hanoi Flood and Storm Control and Dyke Management Department Do Duc Thinh said the municipal authority should put the responsibility on relevant offices who would be held accountable for violations./.