A diplomatic source in Berlin said a German freighter carrying a load of beef to North Korea was told Monday not to dock as planned because some of the beef may contain mad cow disease. The source said the German government ordered the freighter to remain at sea for a week after a German business journal reported last week that some beef shipped from Bavaria was not properly screened for mad cow disease. The ship left Germany early last month with the second load of beef aid and was scheduled to enter the North's Nampo port Monday. A German newspaper said the German government is separating 1,400 tons of the suspected beef from the 6,000 tons heading to the North as the third beef aid shipment.