"Under US regulations, the backbone, or vertebral column, that was exported to Japan is not a specified risk material because it was in beef under 30 months," US Agriculture Secretary Mike Johanns said. "However, our agreement with Japan is to export beef with no vertebral column and we have failed to meet the terms of that agreement."

Mr Johanns said it was dispatching a team of US Department of Agriculture inspectors to Japan to re-examine all shipments currently awaiting approval.