BEIJING - Seven people have been arrested and another detained after police traced the origin of a new variety of clenbuterol, an illegal additive found in pig's feed.

Five suspects from a feed premix company in Fujian province are charged with supplying the chemical, while two feed dealers from Zhejiang province are accused of possessing the illegal additive.

A professor surnamed Zou at Zhejiang University, who was found to be keeping 1,500 kilograms of feed containing Phenylethanolamine A, a new variety of clenbuterol, is in criminal detention.

Police in Yueyang, Hunan province, announced the arrests on Sunday.

Clenbuterol, an additive known as "lean meat powder", is used in pig feed to speed up muscle building and fat-burning, resulting in leaner pork.

However, humans eating food containing clenbuterol can suffer nausea, headaches, limb tremors and can even cause cancer.

The Ministry of Agriculture banned the use of Phenylethanolamine A in feed or animal drinking water at the end of last year. It also announced in April that it will cooperate with eight ministries and commissions to launch a one-year crackdown on toxic additives.

The move followed a clenbuterol pork meat scandal that was exposed on March 15 by China Central Television.

In a separate case, police in Sichuan province on July 3 cracked a case involving the sale of 12,399 kilograms of clenbuterol. The haul was valued at 15.8 million yuan ($2.45 million), the biggest so far.