TIANJIN, CHINA // Wild claims have spread in China suggesting serious misfortune may have befallen the vice president, who was absent from the public eye for an 11th day yesterday.
Authorities have been tight-lipped over the whereabouts of Xi Jinping, 59, who is expected to take over from the Chinese president Hu Jintao as China's top leader in a transition due to begin this year.
Unconfirmed reports have talked of anything from a mild heart attack to a dramatic assassination attempt in which Mr Xi was injured when a vehicle he was travelling in was targeted by individuals loyal to the fallen former Chongqing Communist Party secretary, Bo Xilai.
While analysts suggest a more mundane reason, such as an injured back, is the probable explanation for why Mr Xi has not been seen since September 1, the rumour mill has been stoked by the refusal of officials to give information.
This week, a Chinese foreign ministry spokesman even declined to answer when asked if Mr Xi was still alive.
The lack of official information suggests the country's leaders do not appreciate that the need for openness has grown, said Joseph Cheng, a political-science professor at the City University of Hong Kong.
"They fail to understand, with the increasing importance of China and the coming party congress why people are having a heightened interest in the situation," he said, referring to the meeting at which China's next generation of leaders will be selected.
"The foreign ministry probably understands that honesty is the best policy, [that] you have to announce to the public, to the international community, but I think they also realise that the top leadership treat their health status as a kind of confidential information, a kind of state secret.
"Therefore they cannot afford to displease or antagonise the top leaders. That's exactly why they've been keeping quiet." Mr Cheng said he thinks there is an innocent reason behind Mr Xi's absence from public view, such as a minor health problem.
Among those Mr Xi has cancelled meetings with is Hillary Clinton, the US secretary of state, who visited China last week.
One of the most outlandish rumours is that Mr Xi lost consciousness and was taken to hospital when the vehicle he was travelling in "was sandwiched by two off-road jeeps" on Tuesday night last week, according to the Taiwan-based China Times, citing the Chinese website Boxun.
The report said He Guoxiang, who like Mr Xi is a member of China's nine-strong supreme politburo standing committee, had been hurt in a similar incident soon afterwards.
Both events were said to be the work of a military official who was an ally of Mr Bo, who was removed as Chongqing party secretary in March and now faces corruption allegations.
The Boxun reports cannot be verified and are among a series of explanations put forward, with others including the claim Mr Xi has had a stroke, suffered a mild heart attack while exercising or has been injured while swimming or playing football.
Mr Xi is not the first Chinese leader whose absence this year has raised eyebrows. There was speculation in late March that Zhou Yongkang, another member of China's politburo standing committee, was in trouble politically after he was reportedly not seen in public.
Analysts speculated he may have been removed from power because he was close to Mr Bo, although Mr Zhou soon resumed public duty.
The situation is more sensitive regarding Mr Xi, as he is set to become party chief and Chinese president, and because the party congress where the new leadership will start to take over is probably only weeks away.
Although speculation will probably end only when Mr Xi makes a public appearance, Mr Cheng said that there were no other indications of behind-the-scenes turmoil.
Although Mr Xi has been out of view, other senior leaders such as Mr Hu and the premier, Wen Jiabao, have been making scheduled appearances, indicating nothing serious is happening behind the scenes.
"At the moment, we have not detected any signs that there are major changes in the leadership succession process that will be announced at the coming party congress," he said.
& Daniel Bardsley on