UPDATE 2-Russia bans pork imports from 4 US plants -USDA

(Recasts, updates with USDA comment that ban may relate to antibiotic tetracycline)

By Bob Burgdorfer

CHICAGO, April 29 (Reuters) - Russia, a leading market for U.S. pork, has banned pork imports from four U.S. plants amid concerns about an antibiotic in the meat, the U.S. Agriculture Department said on Tuesday.

News that Russia banned pork from two Tyson Foods Inc. (TSN.N: Quote, Profile, Research) plants and two Farmland Foods plants sent U.S. hog prices sharply lower at the Chicago Mercantile Exchange.

Russia claimed the antibiotic tetracycline was found in some of the pork, the USDA said on Tuesday after reporting the ban on its Web Site late on Monday.

"These things come up occasionally, even with Russia. They claim they have found tetracylcine showing up," said USDA spokesman Keith Williams.

Williams said such things usually are resolved quickly, possible "in a matter of couple of weeks."

The U.S. Meat Export Federation, plus meat companies Tyson Foods Inc. and Smithfield Foods Inc., said they were investigating Russia's action. Farmland Foods is a unit of Smithfield Foods.

The affected plants include the Tyson's facilities in Storm Lake, Iowa, and Logansport, Indiana; and the Farmland Foods' plants in Crete, Nebraska, and Monmouth, Illinois.