China\'s huge online police force is apparently censoring Internet discussion about former president Jiang Zemin, whose absence from a key Communist Party event sparked rumours he was seriously ill. The 84-year-old failed to appear at celebrations marking the 90th anniversary of the Communist Party on Friday, just as Hong Kong media reported he was ill, launching a frenzy of speculation online. His absence was conspicuous as numerous other retired party and national leaders including former prime ministers Li Peng and Zhu Rongji were present at the gala at the Great Hall of the People in central Beijing. On Wednesday, the nation\'s Twitter-like Weibo service censored terms such as \"Jiang Zemin\", \"myocardial infarction\" and \"general secretary\", prompting speculation Beijing is blocking information about his health from leaking out. Hong Kong and overseas Chinese press has reported that Jiang, a former party general secretary, suffered a heart attack and is surviving on a respirator. Other media outlets, however, have said his health is not in danger. The government has long viewed the health of the nation\'s top leaders as a state secret, apparently due to concerns illness might affect the appearance of unity and political stability in the ruling party. China\'s foreign ministry refused to comment when asked about Jiang\'s state on Wednesday. According to one Weibo posting, the propaganda bureau has issued an edict banning news reports on the health of Jiang, who was widely seen as wielding huge influence over a change in party leadership slated for next year. \"About the news that Jiang Zemin has passed away, news organisations can\'t do reports on their own, all news reports should be in accordance with news releases from Xinhua (state news agency),\" the posting said. The alleged edict could not be independently verified by AFP. According to other unconfirmed Internet postings, Jiang is currently being treated at the 301 military hospital in Beijing, where top Chinese leaders often receive medical care. Jiang was last seen in public at the side of President Hu Jintao during celebrations marking the 60th anniversary of the founding of the People\'s Republic of China, in October 2009.