About 85 percent of Ha Noi's ice-making enterprises are unlicensed and do not meet hygiene-and-food-safety-standards, municipal Health Department figures show.

Department director Le Anh Tuan reports that only 42 of the city's 200 ice-making factories hold the supposedly compulsory licence.

"The remainder are mostly business households that are limited to making block ice for frozen food although some of it goes to beverage shops or bia hoi restaurants," the director said.

The director said although regulations governing unhygienic food and beverage was issued several years ago, violations were difficult to detect because the offenders " constantly moved their premises" to avoid inspectors.

Punishments were also too lenient – a fine of about 10-15 million VND (526-789 USD).

PhD Trinh Le Hung from the University of Natural Sciences said water must be drawn from about 90m deep beneath the ground and then specially cleaned before it is made into ice.

Unhygienic ice was extremely dangerous as bacteria and toxic chemicals could long survive in a frozen environment, he warned.

National Institute of Tropical and Infectious Diseases deputy director Dr Nguyen Hong Ha said unhygienic ice could cause acute diarrhoea, cholera and damage the liver and kidneys.

Last month, the institute received 38 patients suffering from acute diarrhoea, two of which were in critical condition. The patients had consumed unhygienic street food.

Health Department director Tuan said the department would increase their inspections of ice producers and disseminate information encouraging people to change their eating habits.

"Once consumers say no to unhygienic food and beverages, the producers of these products will go out of business," Tuan said./.