According to the Associated Press, Japan has suspended beef shipments from an American meatpacker over its failure to remove cattle parts banned under a bilateral agreement, as Japanese officials raise concerns about U.S. safeguards against mad cow disease. Japanese quarantine inspectors found bovine spinal columns in one of 732 boxes shipped from Tyson Fresh Meats Inc., which arrived in Japan in late September, the Ministry of Agriculture, Forestry and Fisheries said. The box contained 35 pounds of chilled short loin with spinal bones, which were not released commercially, said ministry official Goshi Nakata. The suspension only affects Tyson''s factory in Lexington, Nebraska, one of 46 meatpacking plants approved to export beef to Japan. It was the second suspension for the Lexington factory, Nakata said. Japan slapped a four-month ban on beef shipments from the same plant in February 2007 after finding two boxes of beef lacking verifications to show they came from cattle that met Japan''s safety standards. Japan''s new ruling Democratic Party has proposed a tough response to any violation to a bilateral safety agreement, including a blanket ban on U.S. beef shipments. The Japanese ministry has asked the U.S. Department of Agriculture to investigate how the box containing the banned parts ended up in Japan. Japan will await results of a U.S. investigation to determine the penalty for the Tyson factory, the ministry said. Gary Mickelson, a spokesman for Tyson, called the delivery of that box a mix-up. He said the Springdale, Ark.-based company is investigating it and will work with the Agriculture Department to "take corrective measures" so the plant can start supplying Japanese customers again. Washington has repeatedly criticized Japan for its tough import restrictions, which authorities say have no scientific basis. Under the bilateral trade agreement, U.S. exporters must remove spinal columns, brain tissue and other parts considered linked to mad cow disease. U.S. beef shipments to Japan must also come only from cattle age 20 months or younger, which are believed to pose less of a risk. U.S. officials have urged Japan to allow imports of beef from cattle aged at least up to 30 months, a widely used safety standard elsewhere, and possibly scrap age restrictions. Japan banned all U.S. beef imports in 2003 after the first case of mad cow disease was discovered in the United States. Japan resumed buying American beef in 2006 after the bilateral trade agreement setting new safety standards.