TOKYO （AP） -- Japan has suspended beef shipments from an American meat-packing plant after finding cattle parts banned under an agreement to prevent the spread of mad cow disease, the agriculture ministry said Saturday.

Japanese quarantine inspectors found bovine spinal columns in one of 732 boxes sent by Tyson Fresh Meats, Inc., which arrived in Japan last month, the Ministry of Agriculture, Forestry and Fisheries said in a statement. The box contained 35 pounds （16 kilograms） of chilled short loin with spinal bones.

The suspension only affects Tyson's factory in Nebraska, one of 46 meat-packing plants approved to export beef to Japan.

The Japanese ministry also asked the U.S. Department of Agriculture to investigate how the box containing the banned parts ended up in Japan.

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 a bilateral trade agreement setting new safety standards.

Mad cow disease, formally known as bovine spongiform encephalopathy, is a degenerative nerve disease in cattle. In humans, eating meat products contaminated with the illness is linked to variant Creutzfeldt-Jakob disease, a rare and fatal malady.

Under the bilateral trade agreement, U.S. exporters must remove spinal columns, brain tissue and other parts considered linked to the 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.

Washington has repeatedly criticized Japan for its tough import restrictions, which authorities say have no scientific basis.

U.S. officials have urged Japan to allow imports of beef from cattle aged up to 30 months, a widely used safety standard elsewhere.

日本发现从美国内布拉斯加进口的牛肉存在疯牛病风险，暂停进口

日本农业部于周六表示，日本发现了从美国进口的牛肉中含有禁止疯牛病传播协议中所禁止进口的部分，随即暂停从美国进口牛肉。

日本农林渔业部在声明中表示，检疫人员在对上月到达日本的732个货箱进行检查时发现一箱从泰森鲜肉品公司进口的牛脊肉。该箱包含35磅（即16公斤）的冷冻脊骨腰肉。

此次暂停进口只影响到内布拉斯加州的泰森鲜肉品公司的业务，该公司是批准向日本出口牛肉的46家肉类企业之一。

日本农业部门也要求美国农业部就包装内如何含有日本停产的禁止牛肉进行调查。

自美国发现第一类疯牛病后，日本就曾于2003年停止任何美国进口牛肉。但双方就新的安全标准达成协议后，日本于2006年恢复美国牛肉进口。

疯牛病，是牛棉状脑病的俗称，是发生在牛身上的一种变性疾病。人类吃了患有此病的肉类产品后会感染克雅病，这是一种罕见的致命疾病。

在双方达成的协议下，美国出口商必须去除有可能导致疯牛病的牛脊肉、脑组织以及其它部分。从美国到日本的牛肉运输业必须在20个月以下，据说，这是产生危险最小的时期。

美国一再谴责日本毫无科学依据的严格进口限制。

美国政府官员强烈呼吁日本允许进口30个月大牛的肉，这是其它国家普遍使用的安全标准。