China will block imports of pork from Canadian company Frigo Royal Inc after a banned feed additive, ractopamine, was found in a Canadian-supplied pork company.

Ractopamine is used by pork producers in some countries to grow lean pigs, but China does not permit its use and does not allow residues of this drug in imported meat.

China will also strengthen inspections for ractopamine residues in all pork imports from Canada, the Xinhua News Agency reported citing customs. The Xinhua News Agency said that on June 3, Chinese customs authorities in the port of Nanjing discovered ractopamine residues in a pork shipment.

China said it would open all containers of Canadian meat and meat products, and in some cases 100 percent of the contents would be checked. Due to labeling problems, China has already stopped importing pork from two other Canadian producers, Olymel LP and Drummond Export.

He also blocked the import of Canadian canola seeds. Canadian government officials said that China warned them this month that it would strengthen inspection of meat imports after "recent cases of non-compliance" with pork supplies.