Where is China's president-in-waiting Xi Jinping?

Try and search for the name of the man who is widely believed to be about to become the next President of China, Xi Jinping, on Chinese social media and you'll find the request blocked by China's censors, also banned are 'vice president' and 'back injury'.

Xi Jinping hasn't been seen for 9 days and simply asking online about his whereabouts is proving to be too 'sensitive'. In any other country if a senior leader went 'missing', without an official explanation, there would be a national crisis. Can you imagine if Joe Biden went AWOL for 9 days and the White House was saying nothing?

Last Wednesday, Mr Xi cancelled a meeting with Hillary Clinton, the US Secretary of State. Rumours followed suggesting he had hurt his back getting out of a swimming pool. It's also been claimed that Xi is in a military hospital in Beijing.

Then on Saturday, Mr Xi failed to appear at a hastily arranged meeting of the Central Military Commission to plan the army response to the earthquakes in SW China which left 86 dead and thousands homeless.

Last Friday, reporters were invited for a photo opportunity between Mr Xi and Helle Thorning-Schmidt, the prime minister of Denmark.

However, the meeting between the two, scheduled for today at the Great Hall of the People, didn't take place. Instead, Mrs Thorning-Schmidt met with Wang Qishan, a Chinese vice premier.

A spokesman for the Foreign ministry denied a meeting between Mr Xi and Mrs Thorning-Schmidt had ever been intended.

During a regular press briefing he was asked where Mr Xi was, he replied: "We have told everybody everything." As always the health of China's leaders is considered a state secret.

He Guoqiang, another member of China's all-powerful Politburo Standing Committee, has also disappeared. Mr He hasn't been seen since August the 31st.

Boxun, a US based website with close links to dissidents suggested that the two men had been involved in staged car crashes, however the website has now retracted the claim.

Xi Jinping, China's vice president, is due to be unveiled as the new President when the Communist Party holds its Congress in Beijing, the meeting is expected to start next month.