Eight suspects were detained in Jiangxi Province for illegally putting the chemical substance clenbuterol into veterinary drugs in a crackdown by police in 21 provincial regions, the Ministry of Public Security said Sunday.

Some 4,000 boxes of over 20 sorts of such drugs were also confiscated in an effort to secure food safety at its source. The crackdown followed a tip-off in February saying that the pigs raised in Zhejiang Province tested positive for the banned substance in their urine.