But importers must certify that all such products have been cooked at temperatures above 71 degrees Celsius to ensure there is no virus present. The city's action follows a central government directive earlier this week, reports Shanghai Daily.

Shanghai also reported yesterday that the 13 Chinese and five expatriates who are being held under quarantine in the city continued to remain in good health. The group includes passengers who, before arriving in Shanghai, were on a flight last Friday from Detroit to Tokyo with three Japanese travelers who tested positive for swine flu. Also held are people who had come in contact with them.