The ban followed a request last month by Deputy Prime Minister Hoang Trung Hai who is concerned about environmental pollution of the surroundings, including water supplies and good farm land..

In a document sent to departments, People's Committee Vice-chairman Nguyen Ngoc Tuan asked the municipal Department of Planning and Investment to work with other agencies to study specific measures and report to the committee.

He also asked the Department of Industry and Trade and management boards of industrial and processing zones to tell investors to promptly complete sewage-treatment systems and connect them to factories operating in the zones.

Local authorities responsible for industrial zones have also been told to speed up inspection of environmental protection measures.

Figures from the Department of Industry and Trade show that as many as 107 industrial clusters are under construction in the province. Of the 42 industrial zones and clusters in operation, only 25 have the required sewerage systems.

Ha Noi People's Committee has approved a plan to force all industrial zones to use waste-water treatment systems, including assistance from city funds.

The systems will be built at seven industrial clusters this year, and at nine more next year.