South Korea has imposed ban on the imports of beef from the US after finding a banned feed additive, zilpaterol, in a 22-ton meat shipment.
Zilpaterol is a feed ingredient used to boost marketable meat in cattle.
Due to raising concerns over the drug's impact on health of cattle, American pharmaceutical company Merck banned sales of zilpaterol-based drug Zilmax on 16 August.
South Korea Ministry of Food and Drug Safety noted that an investigation revealed the presence of zilpaterol in meat supplied by Swift Beef, a subsidiary of JBS USA, and all the shipments from the company were immediately suspended.
The ministry has asked the US authorities to investigate the case.
In the first nine-months of the year, the country has imported a total of 75,426 tons of US beef; Swift Beef represented about 6% of total US beef imported to South Korea, according to the ministry.
A ministry official was quoted by The Wall Street Journal as saying, "We'll conduct tests on other U.S. beef imports on a random basis and expand checks to meat from all U.S. beef processing sites if we find more Zilpaterol."
Earlier, South Korea banned US beef imports after mad cow case in 2003. The imports were resumed in 2008 despite widespread street protests against the government's decisions.
