7:30PM BST 12 Sep 2012
Xi Jinping is expected to be unveiled as the leader of the Communist party in the coming weeks, but his disappearance from the public eye has sparked increasing speculation.
"Although people have said he suffered a back injury, he actually had a heart attack, a myocardial infarction," said Li Weidong, a political commentator in Beijing and the former editor of China Reform.
The magazine is influential among Chinese policymakers and under the aegis of the National Development and Reform Commission.
Other unnamed sources have also suggested that Mr Xi, 59, suffered a heart attack, while Willy Lam, the former editor of the South China Morning Post, believes China's president-in-waiting had a stroke and is currently unable to show his face in public.
Mr Xi has not been spotted since September 1 and cancelled a series of meetings with foreign leaders, including one with Hillary Clinton, the US secretary of State, on September 4.
