BEIJING, Dec. 11 (Xinhua) -- The Ministry of Health spokesman said Monday that China had not seen any new cases of animal or human bird flu infections since the onset of winter.

    However, spokesman Mao Qun'an warned medical institutions not to relax strict monitoring of influenza and undefined respiratory diseases.

    "We should further improve our reporting of deaths resulting from unknown causes," he said.

    About 47,000 poultry birds died in ten outbreaks of bird flu inseven provinces in the Chinese mainland this year, with another 2.94 million fowls culled, said the Ministry of Agriculture in November.

    The cases of human infection from bird flu numbered 13 this year, six more than last year.

    According to China's lunar calendar, Nov. 7 marks the official beginning of winter.