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A massive hacker attack has crippled an overseas website that has reported extensively on China's biggest political turmoil in years, underscoring the pivotal role the Internet has played in the unfolding scandal.

North Carolina-based Boxun.com was forced to move to a new web hosting service Friday after its previous host said the attacks were threatening its entire business, website manager Watson Meng told The Associated Press. He believes the attacks were ordered by China's security services, but it isn't clear where they were launched from.

The assaults on Boxun's server followed days of reporting on Bo Xilai, formerly one of the country's most powerful politicians, who was fired as head of the mega-city of Chongqing and suspended from the Communist Party's powerful Politburo amid accusations of his wife's involvement in the murder of a British businessman.

The scandal has deeply embarrassed Communist Party leaders obsessed with controlling their image and imposing strict secrecy over their inner workings.

Six years ago, when Shanghai's powerful boss was toppled, Chinese social media was in its infancy and months went by with no word on the case against him.

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Today, the dynamics have changed, and when the government fails to release information about a key political development, the online rumor mill goes into overdrive, with China's half-a-billion Internet users taking to blogs, foreign news sites, and — most significantly — Weibo, China's hugely popular version of Twitter.

"People on Weibo used to care mainly about lifestyle issues, but this time we're seeing it play an unprecedented role in spreading political information and opinion," said Zhan Jiang, a professor at Beijing Foreign Studies University's School of Mass Media.

The first whiff of the Bo scandal came when his former right-hand man, ex-Chongqing police chief Wang Lijun, breached protocol with a surprising Feb. 6 visit — first reported in Weibo postings — to a U.S. Consulate in a neighboring city. There were rumors of a spat with Bo, but neither Chinese nor U.S. revealed any details of the consulate visit.

At the time, Bo admitted to not properly managing his staff, but it appeared he would keep his job and remain a candidate for the party's all-powerful Politburo Standing Committee when a new generation of leaders is picked this fall.

But then the scandal caught fire with suggestions online that Wang was spreading the word about the alleged involvement of Bo's wife in the death of Briton Neil Heywood, a business consultant with close ties to Bo's family. Those suspicions first appeared in a brief posting in early March by a reporter from the Southern Weekend newspaper group, who said he'd received the information via a Feb. 15 text message from a telephone number used only by Wang.

That happened after Chinese authorities took Wang into custody on Feb. 7, so it wasn't known who sent the message. However, it was widely circulated online, and the foreign media flocked to Chongqing to investigate, making it impossible for the government to ignore the case without sparking an international incident.

A few weeks later, on March 15, Bo was sacked as Chongqing party chief, and on April 10 authorities announced he was under investigation and that his wife and a household aide were suspects in the Heywood murder.

Boxun, which has reported on the scandal since early February, was brought down for several hours Friday in a denial of service attack in which hackers deluge a website to paralyze it.

"We publish articles critical of the Chinese government so we're accused of having ulterior motives," Meng said in an online chat. "But in the West, most media is critical of its government, so why can't we be?" he said.

Foreign governments and corporations routinely complain of hacking attacks from China, although it is rarely provable where they originate or who is behind them. The Chinese government routinely denies using hackers to attack web sites or steal secrets online.

Meng set up Boxun in 2000 to spread word on the pro-democracy movement, human rights, and corruption, much of it submitted by readers in a form of citizen journalism. Its edgy nature has brought it under hacker attack before and forced it to go without advertising since 2005. Meng says Boxun is independently financed, although the U.S. government-funded National Endowment for Democracy has partly backed the China Free Press project managed by Meng and registered at the same address as Boxun.

Not all of Boxun's reports have held water and it has offered competing accounts of what drove the decision to cashier Bo. But many of its reports on allegations of Gu's involvement in the Heywood death and the Bo's falling-out with Wang have since been proven true or been corroborated by other sources.

Traffic to the site has grown 155 percent over the past three months, according to Internet monitoring firm Alexa, with the second largest chunk of visitors coming from China, despite government blocks.

China heavily censors the Internet and blocks Twitter, Facebook, YouTube and scores of other overseas sites. Government monitors swiftly remove sensitive postings and have tried to rein in Weibo by requiring proof of identification for new accounts and sometimes disabling sections where comments can be posted.

Still, the sites have a profound effect. Witness reports on a horrific train collision last year prompted disgust at officials' callousness and a sweeping safety review.

One reason why the government may not have cracked down harder on the Internet so far is because parties within the establishment also use it to attack their foes, spread disinformation or advance their own agendas, said Xiao Qiang, director of the China Internet Project at the University of California-Berkeley.

But they can't completely control the online discussions or filter out all unwanted revelations, Xiao said.

"Those facts and opinions generate pressure or create the conditions for the government to take actions such as firing Bo Xilai," he said.