The nation's top pharmaceutical regulator on Sunday announced it had revoked the production licenses of another two gelatin-capsule producers in East China's Zhejiang province amid a scandal over chromium-tainted drug capsules.

According to a statement on the website of the State Food and Drug Administration, the Zhejiang provincial drug authority was ordered to revoke the licenses of the Chuangshi Capsule Co Ltd and Linfeng Capsule Co Ltd.

The two companies committed "grave violations of laws and regulations", and those suspected of criminal offenses may face charges, it said.

The action brought to five the number of gel capsule makers that have had their production licenses revoked, according to information on the SFDA's website.

Since the scandal was exposed by China Central Television on April 15, public security authorities have closed 10 companies, detained 53 people and seized some 230 tons of industrial gelatin, according to the central government.

The companies allegedly produced and sold capsules made with industrial gelatin, which contains a much higher level of chromium than edible gelatin.

Excessive intake of chromium can result in chronic diseases, experts said.

In response, the Ministry of Health on Saturday asked medical institutions at all levels to cooperate with drug authorities to recall tainted medicines.

It also ordered them to stop buying and using the 13 types of problematic medicines produced by nine pharmaceutical companies. The SFDA said on Saturday that more inspection teams have been sent to investigate the capsules and identify those responsible.

Inspection teams from departments, including the police, the health authorities and supervisory agencies, have been sent to Zhejiang, Hebei and Jiangxi provinces to supervise the investigation of the case locally, said the administration.

The investigation has also led to an overhaul of the production of nationwide drug capsule makers and manufacturers of gelatin for medical use.

The SFDA held a meeting on Friday, asking local drug authorities to inspect those enterprises' raw materials and their sources and to conduct an audit of suppliers, products and their destinations.

Those who refuse to cooperate and try to cover up malfeasance will be severely punished, it said.

Supervisory agencies have started investigating officials for possible dereliction of duty, it added. The SFDA also promised to make public announcements on the progress of the investigation.

Song Jiangxin, former chairman of the National People's Congress of Wangji village in Fucheng county, Hebei province, had his Communist Party of China membership and administrative position revoked after telling Liu Aiguo, a worker at the local Xueyang Glair gelatin factory, to set fire to the plant to eliminate evidence, Xinhua reported on Sunday.

Song is the younger brother of the legal representative of the factory. Song and Liu were detained by police on Saturday.

Wang Chengdong, an administrative law professor at the China University of Political Science and Law, said the tainted capsule scandal showed that these products weren't yet being efficiently supervised.

"They are treated as neither food nor drugs. Related authorities have limited knowledge about how capsules would affect people's health", he said.

Wang said the government and supervisory bodies should take some responsibility in capsule production supervision, and any officials who are found "economically connected" with illegal capsule producers or who neglected their duty should be severely punished.

Contact the writer at chenxin1@chinadaily.com.cn