Twelve people were caught producing and selling fake animal drugs, said police in east China's Shandong province on Wednesday.

Police in Jinan, Shandong's capital, also seized more than 7,000 kilograms of fake drugs.

The food and drug watchdog in Jinan city was tipped off last November about a company adding components from medicines for humans into animal drugs.

According to Zhang, head of the group, they founded the company Jinan Tongran in May 2013, in which they manufactured 120 fake animal drugs under big brands, before selling them to more than 20 provinces, municipalities and autonomous regions in China.

Police found that the drugs were mostly sold to wholesalers, veterinary stations, breeding companies and farmers. They estimated that more than 150 million yuan (about 23.5 million U.S. dollars) was involved in the case.

Further investigation is under way.