BEIJING, Feb.16 -- More than 40 per cent of fish species in East China's Jiangsu Province were found to be contaminated with heavy metals, according to a survey released by Jiangsu Environment Monitoring Centre (JEMC) this week.

Last year's investigation covered the province's major fo ur freshwater lakes and offshore areas, reported the Nanjing-based Contemporary Post.

Cadmium, lead, mercury, chromium and zinc were the five kinds of heavy metals found in 41 per cent of species in the sample survey.

It revealed seashells, shellfish, and large-sized fish are the three types of species that suffer from the most severe contamination.

But Xia Yu, director of the fishery department with Jiangsu Oceanic and Fishery Administration, questioned the liability of the statistics released by JEMC, which is not specialized in fishery products.

According to Xia, surveys carried out by his department in 300 water areas over the past five years showed only 3 per cent of fish species tested were polluted with heavy metals.

"JEMC's research methods and sample selection might be different from us, so we obtain different results," said Xia.

Experts have now urged consumers to be cautious about eating too many of the products.