Japan has suspended beef shipments from an American meatpacking plant over worries about mad cow disease.

Japan's agriculture ministry says quarantine inspectors found bovine spinal columns in one of more than 700 boxes of beef sent by Tyson Fresh Meats, Inc., which arrived in Japan last month. Those are among the cattle parts banned under an agreement to prevent the spread of mad cow disease.

The suspension only affects Tyson's factory in Lexington, Neb.

Japan slapped a four-month ban on beef shipments from the same plant in February 2007 after finding two boxes of beef lacking verification that they came from cattle that met Japan's safety standards.

The Japanese ministry also asked the U.S. Department of Agriculture to investigate.