Prosecutors have begun investigating local drug companies and distributors suspected of rigging bids in the government’s drug procurement projects.

The Seoul Central District Prosecutors’ Office said Wednesday that its investigators raided more than 10 pharmaceutical manufacturers and distributors who are suspected of forming an illegal cartel to rig bids in a government tender for the procurement of drugs.

The prosecution reportedly found some additional evidence of collusion of pharmaceutical companies and distributors while conducting probes based on the Fair Trade Commission’s complaint.

In May, the antitrust watchdog slapped the fine of 990 million won ($845,481) on a local firm, which exclusively imports BCG (Bacillus Calmette–Guérin) vaccine from a Japanese drugmaker, for intentionally stopping orders of cheap intradermal BCG vaccine to increase the sale of expensive percutaneous BCG vaccine.

BCG vaccine is used for babies against tuberculosis.

Along with the suspected price-fixing, prosecutors will look into allegations that some companies supplied risky vaccine products even though they were aware of their side effects and risks.