The illegal dredging had been going on over at least five months near the village in Bot Xuyen commune, My Duc district, said Commune People’s Committee deputy chairman Le Ngoc Thuc, and both banks had become susceptible 16 erosion, especially in rainy season.

The sand was being removed from about 4km of the river at the rate of about 1,000 cu.m every day, with the noise of dredges disturbing residents.

Local authorities had patrolled the area and issued fines in hundreds of cases, but the dredging continued, putting the houses of more than 60 families in danger of collapsing.

Several had already begun cracking. One of the problems was that Bot Xuyen commune was assigned to manage one bank of the river while Vien Noi commune managed the other, Thuc said.

Whenever authorities from one commune approached, the dredges moved to the other bank to avoid being fined and there was a lack of co-ordination between each commune. In 2007, the People’s Committee joined local police to use a canoe to chase the sand dredges, but the crews resisted strongly.

In June this year, the Ha Noi Department of Natural Resources and Environment and the city police decided to fine each dredge owner VND200,000 (US$10), but "the punishment was not strong enough" to be a deterrent.

"To prevent the illegally exploitation, we need help from Vien Noi commune and assistance from the upper authorities," Thuc said. Meanwhile, Vien Noi People’s Committee chairman Truong Van Hai said dredging had put the river bank at high risk of landslides in the wet season, and "threatened the lives and farmlands of more than 400 families. "We are ready for co-ordinating with Bot Xuyen commune to find ways to prevent the problem," Hai said.