China has detained 37 people on Wednesday linked to a vaccine scandal and also are investigating three pharmaceutical companies.
The case includes almost $90 million worth of illegal vaccines against meningitis, rabies and other illnesses, that are suspected of being sold in dozens of provinces around China since 2011.
The vaccine scandal emphasises the challenge the world's second-largest drug market faces to regulate its fragmented supply chain, even if Beijing is willing to support home-grown firms.
"This vaccine safety case has drawn close attention, and shows there are many gaps in terms of regulation," Li said in a statement posted on the central government's website late on Tuesday.
Three pharmaceutical companies are being investigated by police, according to the work group handling the case. Of the three, Shandong Zhaoxin Bio-tech Co. has had its good supply practice certificate for pharmaceutical products revoked and ordered to halt operations.
According to a notice from the Shandong Public Security Department, a mother and daughter bought vaccines illegally from traders, then sold to many of the re-sellers around China.
Also police said China's top court would oversee the vaccine case directly.
"Dereliction of duty would not be tolerated, and authorities should improve both regulatory and security system surrounding vaccine production and distribution," Chinese Premier Li Keqiang said.