China's top drug authority revoked the production licenses of two gel capsule manufacturers in Zhejiang province amid a scandal over chromium-contaminated medicine capsules.

Since the scandal was exposed by a China Central Television report on Sunday, police have detained 32 people who allegedly produced and sold capsules made from industrial gelatin, which contains excessive levels of chromium.

According to an online statement issued by the State Food and Drug Administration on Thursday, the administration ordered the Zhejiang provincial drug authority to revoke the production licenses of the Huaxing and Zhuokang plants for unspecified "grave violations of laws and regulations".

Those suspected of criminal offenses will face charges, it said, and investigations into other companies are under way.

At present, the Ministry of Public Security has closed 10 companies and detained 53 people.

On Thursday, Changchun-based Xiuzheng Pharmaceutical Group said it has recalled products with tainted capsules and apologized to the public on its website. The drug safety watchdog promised to strengthen monitoring and firmly crack down on the illegal use of industrial gelatin to produce drug capsules.

According to Sun Zhongshi, an expert with the National Rational Drug Use Monitoring System under the Ministry of Health, current regulations require drug authorities to only check the quality of active ingredients of drugs before they enter the market.

"The relatively lax quality check of non-active pharmaceutical products like medicine capsules has become a loophole used by profiteers," he said, urging authorities to fix the situation.

In response, Minister of Health Chen Zhu said government supervision of non-active pharmaceutical products should be improved.

"China is huge and has so many companies. High quality of drugs could hardly be achieved merely by government supervision," he said. However, Chen urged the public to have confidence in the nation's health and drug industry.

On Wednesday, the central government issued a circular addressing the issue of medicine quality and pledging to resolutely crack down on related offenses.

Sun agreed with Chen, saying that some underground factories, producing problematic capsules, were not registered with local drug authorities, making supervision impossible.

Yu Guoqing, who ran a company producing medicine capsules in Xi'an, Shaanxi province, said they couldn't compete with the capsules made in Zhejiang that sold for less than half the price.