China will step up monitoring of a faulty rabies vaccine that has been recalled but may still be on the market, the country's Food and Drug Administration said Friday.

Although the vaccine was recalled and production shut down late last year, China's lax regulatory environment means doses of the vaccine may still be on the market. The administration also said it was watching for any reactions in people who took the vaccine last year.

It is the latest in a series of quality problems in China in recent years, including tainted infant formula and other milk products that sickened children.

More than 200,000 units of the rabies vaccines manufactured by Jiangsu Ealong Biotech Co. and Hebei Bioforwell Co. were recalled because they did not meet national quality standards, the administration said on its website.

It did not say what was wrong with the vaccine, or what symptoms people may have who took it. Rabies outbreaks are common in China, with more than 2,000 people dying annually in recent years after being bitten by infected dogs.

Jiangsu Ealong Biotech Co. issued a statement earlier this week saying it had stopped making the vaccine late last year after quality problems surfaced. The administration said Hebei Bioforwell also stopped production last year.

Requests for further information from the administration were not answered late Friday.

China's pharmaceutical industry is lucrative but often poorly regulated. Local manufacturers and other players in the drug supply chain have been blamed in recent years for deaths linked to counterfeit or shoddy medications at home and abroad.