Pharmacy supervision agencies nationwide are required to strictly monitor the confiscated capsules made from toxic industrial gelatin to prevent them from flowing back into the market, said the top drug regulator.

Drug administrative authorities should keep a tight rein on unqualified capsules to make sure that these products are totally destroyed, the State Food and Drug Administration said on Monday on its website.

Nine companies have been accused of manufacturing drug capsules with industrial gelatin, which contains a greater amount of chromium than edible gelatin and may result in chronic diseases if ingested in excessive amounts, according to a report from China Central Television on April 15.

Local drug authorities should take strict measures to stop pharmacy companies from randomly discarding the tainted capsules, said the administration.

The statement came after several cases of capsules were found to have been dumped in Central China's Henan province since the scandal broke.

A large number of unidentified empty drug capsules were found discarded in a gutter in the suburban village of Ligang, in Zhengzhou, capital of Henan province, on April 21.

The capsules dyed the sewage water blue and formed a colorful layer stretching for more than 300 meters. The local drug bureau could not confirm whether the water and soil had been contaminated.

Sun Baozhou, the Party chief of Ligang village, said that there is no pharmaceutical company near the village, and the local government is probing the case.

"We are going to check the local residents' homes one by one to find out whether any illegal capsule-making workshops are being hidden in the villagers' houses," Sun said.