NANNING - South China's Guangxi Zhuang autonomous region is to close more than 100 of its heavy-metal processing plants, in an effort to lessen pollution, it has been announced.

Government authorities have performed a comprehensive inspection of such industrial facilities in Guangxi, screening 154 plants against pollution control regulations, Liang Bin, chief of the region's environmental protection department, said on Monday ahead of World Environment Day falling on Tuesday.

Among the plants, 31 were required to take correctional measures before resuming production, and the other 123 were ordered to close, said Liang.

The inspection was initiated after cadmium contamination was detected in January on the Longjiang River in the region's Hechi city. It killed a large number of fish and threatened the drinking water supply for Liuzhou, a city with 1.5 million residents.

Two chemical companies were later found responsible for causing the contamination through illegal industrial waste discharges, and 10 of their managers were arrested for trial.

Guangxi is rich in nonferrous metal resources, and Hechi city is dubbed "a land of nonferrous metal."

Liang said heavy-metal pollution control is challenging in Guangxi because of the region's limited budget and lagging production technologies.

The region has earmarked 25 million yuan ($3.9 million) this year to support 11 projects on heavy-metal pollution control and applied to central government for financial support with another 126 similar schemes, with total spending of 4.5 billion yuan applied.

"We will further strengthen industrial supervision, upgrade requirements for new companies involving heavy metal, and facilitate the phaseout of backward production capacity," according to Liang.