SEOUL, South Korea — South Korea said Tuesday it found bones, banned because as a mad cow disease prevention, in the latest shipment of American beef and will revoke import approval for JSP Swift’s plant in Grand Island, the U.S. packing plant that processed it.

The packing plant was already suspended from shipping meat to South Korea since July, said JSP Swift spokesman Marco Sampaio.    The latest shipment was sent before the Grand Island was suspended for a similar violation in July,    

Sampaio said JBS Swift will try to restore the Grand Island plant’s eligibility to ship beef to South Korea.

Meanwhile, the company has other plants eligible to ship beef to South Korea, Sampaio said.    The company added JBS to its name this summer after a Brazilian company, JBS SA, bought it.

The Grand Island plant was one of 36 American plants originally authorized to handle meat for export to South Korea. 

South Korea’s Agriculture and Forestry Ministry said rib bones were found Monday in one box of a 15.5-ton shipment that arrived in South Korea on Aug. 10.

The ministry said it will send the entire shipment back to the United States.

An unidentified plant, now known to be the Grand Island plant, had been suspended from shipping meat bound for South Korea on July 31 for a similar violation.  Now it will be barred from exporting to South Korea, the ministry said in a statement.   The latest shipment had been sent July 29, two days before the suspension, The Associated Press reported.

South Korea previously revoked import approval for another plant and suspended three others from shipping meat after banned bones were discovered in shipments to South Korea.

The government’s latest move — which came a week after Seoul resumed its inspections of U.S. beef — lowered to 31 the number of U.S. plants authorized to process meat bound for South Korea. Seoul had halted quarantine inspections of U.S. beef in early August after discovering a shipment containing a vertebra.

South Korea, formerly the third-largest foreign market for American beef, banned U.S. imports of it for almost three years after mad cow disease was discovered in the United States.

It partially reopened its market last year, but agreed to accept only boneless meat from cattle under 30-months old. Bones are believed more likely to carry the disease.

Scientists believe mad cow disease spreads when farmers feed cattle recycled meat and bones from infected animals. The cattle disease is also believed to be linked to the rare but fatal human variant Creutzfeldt-Jakob disease.