Police will conduct a thorough investigation into biomedical plants and industrial chemical parks in some key areas, according to the Ministry of Public Security.

The probe is aimed at stopping the production of substances related to the drug fentanyl.

The synthetic opioid, which is 50 times more powerful than heroin and 100 times more potent than morphine, is prescribed to treat patients with chronic pain, especially after surgery.

"We will focus attention on eliminating some of the risks relating to the illegal manufacture of fentanyl-related items, destroy some drug dens and confiscate raw materials," said Liu Yuejin, a senior official from the Ministry of Public Security.

From Wednesday, fentanyl-related substances will be added to a supplementary list of controlled narcotics and psychotropic substances used for nonmedical purposes in China.

"Anti-drug officers will take detailed measures to ensure the controls are implemented effectively," Liu said.

He added that police will clean up illegal drug-related information online and cut off channels that enable suspects to make contacts and operate transactions on the internet.

To prevent fentanyl being smuggled overseas, Liu said the authorities will supervise express companies that mail packages, ensuring they bear a client's real name. Packages will also be checked and scanned by machine, while customs officers will be deployed to inspect suspicious items from overseas.

The ministry said police will search for clues relating to the suspected illegal use of fentanyl-related substances and set up a special team to investigate and uncover major cases of manufacturing and smuggling the drug.

China will also deepen judicial cooperation with the United States and other countries on information exchanges and case-by-case negotiations.

Joint investigations will be carried out and action taken to smash transnational drug-trafficking rings.