Chinese authorities have introduced a series of measures to block pork containing the illegal additive clenbuterol from entering the market, the Ministry of Commerce (MOC) said in a statement Friday.

The MOC had sent a working team to central Henan Province, where contaminated pork was found, to help with local government investigations, said the statement posted on the ministry's website.

The Henan MOC office had urged Jiyuan Shuanghui, a subsidiary company of the country's top meat processor Shuanghui Group, to suspend production and launch in-house investigations.

Similar measures should also be implemented at the Nanjing Xingwang slaughterhouse, it said.

It beleived that pigs in Henan were fed on food laxed with clenbuterol, an illegal additive, to produce lean meat which sells for a premium in China.

Besides conducting on-site supervision of companies involved in the scandal, the MOC issued an urgent circular requiring its offices to conduct thorough examinations of local slaughterhouses and strict implementation of relevant quality inspection systems.

The authorities are making efforts to recall the contaminated pork and trace its source and will promptly release information to the public, according to the statement.