Groundless rumours of a coup that have swept Beijing in recent days are a sign of nervousness after the sacking of political star Bo Xilai exposed rifts in China's ruling Communist Party, analysts say.

Bo had been tipped to join an elite group of leaders who effectively run China later this year, and his downfall -- announced last week in a brief official dispatch -- is the biggest drama to hit the Communist Party in years.

But the news has been only lightly covered by China's tightly controlled state media, opening the way for lurid online speculation involving a crashed Ferrari, gunshots and even tanks rolling into central Beijing.

"People are nervous, there's not much information available," Bo Zhiyue, an expert on Chinese elite politics at the National University of Singapore, said Thursday.

"They are hungry for new information, and if there's nothing new, they will make up new information."

Bo, a flamboyant member of the Politburo -- which groups the 25 most powerful politicians in China -- was removed as party chief of the southwestern metropolis of Chongqing last Thursday.

His sacking came weeks after his former right-hand man and police chief Wang Lijun reportedly tried to defect to the United States in a dramatic event that remains shrouded in mystery.

The incident sparked speculation about Bo's future, but his sacking still came as a shock, as the party normally likes to maintain an appearance of unity, which it believes is crucial to preserving stability in China.

The state-run Xinhua news agency -- which reported the news -- gave no reason for Bo's ouster.

So far, the only official information on the subject has come from a brief statement by Li Yuanchao, a powerful party leader, last Thursday that gave no concrete information about the reason why Bo was dismissed.

Since then, rumours -- all of them unverifiable and most of them highly implausible -- have emerged to fill the void of official information.

Rumours of a military coup orchestrated by security czar Zhou Yongkang against some of the top leaders are perhaps the most fanciful.

These emerged earlier this week when netizens started reporting on microblogs that there were tanks on one of Beijing's main thoroughfares and that they had heard gunshots.

Security in the capital has not visibly increased.

An apparently official document that was posted online, alleging that one of Bo's family members was being investigated for corruption before he was sacked, has been given more credence.

The document -- allegedly compiled by the party's highest authority -- reveals Bo reportedly turned on Wang when the latter broke news of the probe to him, prompting Wang's escape to a US consulate to request asylum.

Even a deadly Ferrari crash in the capital has sparked intense speculation over the identity of the driver, after reports of the incident were censored online.

David Kelly, research director at analysis group China Policy, said top authorities were likely trying to contain the effects of Bo's dismissal -- and the rumours.

"The problem is to deal with the aftershocks -- the sudden emotional swings of the public mind," he said.

Search terms such as "gunshot", "tank", "Bo Xilai", "Wang Lijun", Bo's son "Bo Guagua" or his wife "Gu Kailai" have all been censored on Sina.com's popular microblog, or weibo.

"All this is saying that the factional struggle has now burst into the open," said Willy Lam, a China expert at the Chinese University of Hong Kong.