Watch BBC correspondent Henry Tang's report

Seven hundren people were killed in the Tiananmen Square crackdown

Chinese students who supported the pro-democracy movement captured the attention of the world's media with their seven-week occupation of Tiananmen Square in June nine years ago.

However, the most memorable images are of a young man, carrying what appears to be a shopping bag, who refused to move out of the way of the advancing tanks.

He then climbed onto the leading tank and spoke to the driver.

The Information Centre for Human Rights and Democracy Movement in China says it has obtained official documents that show the Chinese government does not know what happened to him.

Although the man was initially identified as Wang Weilin, the documents suggest the name was false.

In response to an inquiry, President Jiang Zemin is said to have blamed journalists for giving authorities the wrong name. The Chinese government gave up looking for the man after checking lists of the dead and imprisoned.

Time magazine has cited the unidentified protester as one of the "top 20 leaders and revolutionaries" of the 20th century.

Dubbing him "the Unknown Rebel," the American news journal said his moment of fame was seen by more people than laid eyes on Winston Churchill, Albert Einstein and James Joyce combined.

Chinese authorities sent tanks into Tiananmen Square in the early hours of June 4, 1989 to break up an extended demonstration by Chinese student activists. Several hundred people were reported to have been killed.