Police in Changchun, Jilin province, have launched an investigation into Changchun Changsheng Bio-tech Co, a major vaccine producer in China, for allegedly making substandard rabies vaccines for human use.

Top officials of the company, including the chairwoman surnamed Gao and four other senior executives, were brought to the police bureau for questioning, the police bureau of Changchun New Area said in a press release on Monday evening.

The safety of vaccines in the country is again in the spotlight, following the announcement of the State Drug Administration (SDA) last week that Changchun Changsheng Bio-tech Co fudged production records for rabies vaccines for human use. The company stopped production after an order by SDA.

Changsheng, a listed company at Shenzhen Stock Exchange, has also been put under investigation by China Securities Regulatory Commission for law violations and irregularities in information disclosure, the commission said on Monday. The company said in a statement on Monday that it faces risks of being delisted.

Changsheng shares, which resumed trading on Monday afternoon session after being suspended in the morning, were down 10 percent. They have slumped 47 percent since mid-July.