BEIJING — China's social-media services, which had allowed wide discussion of controversial politician Bo Xilai since his ouster last week, are now cracking down on searches for his name, as his downfall seems to have put much of the country on edge and given rise to fevered rumors of political infighting.
On Monday night, Internet users were startled by reports—entirely unsubstantiated—on China's wildly popular Twitter-like microblogging sites of gunfire in downtown Beijing. Nerves were further jangled by accounts of a heavier-than-usual police presence along Chang'an Avenue, one of the capital's main thoroughfares.
Among the legion of social-media fanatics, there has been fevered chatter of a political struggle inside the towering walls of the Zhongnanhai leadership compound in downtown Beijing.
One theory, widely explored: A battle is brewing between Zhou Yongkang—the country's domestic security chief who is believed to be a strong supporter of Mr. Bo—and President Hu Jintao, Premier Wen Jiabao and other leaders who analysts say likely supported Mr. Bo's ouster. Mr. Zhou is a member of the party's all-powerful Politburo Standing Committee, and one of the country's nine most powerful political leaders.
The Communist Party's grip on power depends in large part on maintaining a facade of unity, so the online rumor mill is clearly unsettling China's propaganda officials and their armies of Internet censors. That is particularly true in the run-up to a once-a-decade leadership change scheduled to take place later this year.
Rumors of a power struggle also appeared to unsettle markets: Credit default swaps on China's government debt—which offer a sort of insurance if China is unable to pay back its obligations—briefly rose on Tuesday before falling back to previous levels, according to a trader.
On Wednesday, Beijing appeared outwardly calm, though rumors continued to spin around overseas Chinese-language news websites, including that of the Epoch Times, a New York-based news organization with ties to the Falun Gong spiritual group, which is banned in China.
Mr. Bo was dumped last week after a scandal involving his former police chief, Wang Lijun, who apparently sought asylum in the U.S. Consulate in nearby Chengdu. Mr. Bo was a populist politician who grabbed national headlines with a high-profile crackdown on organized crime and attempts to revive the singing of Mao-era revolutionary songs.
For several days after his ouster, censors took a hands-off approach to online gossip, letting speculation flow freely. That changed this week as popular microblogging site Sina Weibo reinstated an earlier block on searches for Mr. Bo's name and additionally blocked a wide range of user-invented code words for Mr. Bo, including the term "not thick"—a play on Mr. Bo's surname, which means "thin."
Searches for Mr. Bo's name, "not thick" and other related terms were also blocked on Tencent Weibo, another of China's popular microblogging sites, which often impose their own blocks in anticipation of what the government will deem sensitive.
In the current overheated atmosphere, unexpected news is being parsed for political meaning. For instance, speculation has swirled about the identity of a man killed on Sunday morning when the Ferrari he was driving crashed into a bridge on a Beijing highway and shattered into pieces. Online rumors that the driver was the son of a high-level central-government official picked up steam after censors moved aggressively to quash discussion of the accident.
Police told local media that the circumstances surrounding the crash, in which two female passengers were seriously injured, are still being investigated.
"I don't recall ever seeing anything like this on the Chinese Internet," said Jeremy Goldkorn, founder of Danwei, a website that tracks Chinese media, of the recent proliferation of political gossip. The presence of so much rumor online is one likely explanation for the stepped-up censorship, he said.
"Things are getting a little too out of control, so they've decided to rein it in," Mr. Goldkorn said, adding that it was difficult to say whether the decision to block searches came from government authorities or the websites' own in-house censors.
Searches for "Ferrari," "coup" and Zhou Yongkang's name were also blocked on Sina Weibo this week. To beat the blocks, users have begun referring to Mr. Zhou as "Kang Shifu," using the name of a drink and instant noodle brand in a wordplay on the last character in Mr. Zhou's name. Sina didn't respond to a request to comment.
The removal of Mr. Bo is widely seen as a major blow to the "new left," a loose collection of academics and lower-ranking officials, who advocated a return to Maoist values and a strong role for the state in economic and political development.
That dynamic is also playing out on the Internet. An essay by one well-known academic defending Mr. Bo's record was published Wednesday on the leftist website Utopia, where a prominent section dedicated to Chongqing was left strangely blank.
The article by Cui Zhiyuan, a professor at Tsinghua University in Beijing and one of the New Left's ideological leaders, argued that both the state and private enterprise had advanced in Chongqing under Mr. Bo's leadership there. Mr. Cui has not responded to requests for comment in recent days.
Meanwhile, in a potential signal that central propaganda authorities have yet to issue clear orders on how to handle Mr. Bo's case, restrictions around the former political star on Baidu, China's equivalent to Google, appeared to have loosened.
Searches for Mr. Bo's name on Wednesday produced a list of results noticeably missing a censorship disclaimer that typically accompanies search results related to top Chinese leaders. While the absence of that disclaimer doesn't necessarily mean results aren't being censored, the search engine appeared to have removed at least some of the filters surrounding content about Mr. Bo.
For example, top results in Baidu searches combining the names of several Chinese leaders and the word "corruption" on Wednesday each pointed to articles discussing those leaders' efforts to fight corruption, whereas the top result in a similar search using Mr. Bo's name was a page on a Baidu question-and-answer forum where users were discussing whether or not Mr. Bo and his forme lieutenant Wang Lijun were guilty of corruption.
Back on Sina Weibo, the combination of stepped-up censorship with a lack of information from traditional media, far from putting a stop to rumors, appeared instead to be feeding more speculation.
"Visiting Beijing right now? Here's a list of keywords," one Sina Weibo user wrote Wednesday afternoon, going on to suggest various arcane combinations of Chinese characters, numbers and English letters that would allow others to discuss Mr. Bo, the Ferrari crash and the coup rumors.
"The strangeness on the 19th..." the user continued in reference to the day the coup supposedly took place, "sends a shiver down my spine. It can't be, can it?"