The U.S. demanded South Korea fully open its beef market, but the Asian nation insisted it would maintain quarantine regulations citing concerns over mad cow disease, South Korea's Yonhap news agency said, without citing any official.
The talks came on the heels of the decision by South Korea to suspend all American beef imports last week after inspectors found banned bones in a shipment.
South Korea agreed last year to import only boneless U.S. meat from cattle less than 30 months old - believed to be less likely to carry the disease - partially lifting an almost three-year ban imposed on American beef after the brain-wasting disease was discovered in the U.S.
The U.S. has pressed for the South Korean beef market to be more open, citing a ruling by the World Organization for Animal Health this year that the U.S. was a "controlled risk nation" - meaning it can export beef irrespective of the animal's age.
The U.S. has said the ruling proves American beef is safe.
Scientists believe mad cow disease, or bovine spongiform encephalopathy, spreads when farmers feed cattle recycled meat and bones from infected animals. The disease is also believed to be linked to the rare but fatal brain-wasting human variant Creutzfeldt-Jakob disease.
South Korea was the third-largest foreign market for American beef before it banned U.S. imports in December 2003.