This file photo taken on April 2, 2012, shows a woman viewing the Chinese social media Web site Weibo at a cafe in Beijing. (Mark Ralston/AFP/Getty Images)

China has unfurled a vigorous new campaign to clean up the Internet, to purge it of everything from pornography to “rumors” that might undermine Communist Party rule, a crusade that critics say is a renewed attempt to silence grass-roots voices and stifle dissent.

Censorship of the media and Internet is routine in China, but controls on online freedom of expression have been steadily strengthened since Xi Jinping took over as president last year.

The new campaign appears to represent a further tightening of the screws, part of a bid to bend the Web to the will and values of the Communist Party — to ensure, in the words of blogger Zhang Jialong, that “party organs, and not the Chinese grass roots, have the loudest voice on the country’s Internet.”

“As social conflicts intensify, particularly between Chinese officials and the people they are supposed to serve, central authorities hope to clamp down, clean up, and suppress any so-called ‘harmful information’ that is disadvantageous to their dictatorship,“ he wrote on the Tea Leaf Nation Web site.

The drive, to “sweep out porn, strike at rumors,” will run from mid-April until November, the party’s news portal Seeking Truth declared this week.

Chinese American investor and blogger (Charles) Xue Manzi embodies, in the Communist Party’s eyes, the twin evils of moral degeneracy and dissent — and the dangers of Western values.

His 14-minute confession for spreading rumors online and visiting prostitutes was broadcast on China Central Television on Wednesday to reinforce the campaign message, four hours after he was released on bail.

Xue was arrested in August on charges of hiring a prostitute, and a first, similar confession was broadcast a few weeks later.

“I lived in the United States for 34 years,” Xue said in this week’s confession, wearing a green prison vest and clutching a red-covered copy of the Criminal Law of the People’s Republic of China.

“I think Western culture had a profound effect on me,” he said. “When it came to engaging in orgies, the alarm did not go off in my head.”

Xue, whose liberal posts had won more than 12 million followers on the Sina Weibo microblogging site, also expressed regret about causing losses to a fish farm by posting that its water contained mercury.

He let his huge Weibo following go to his head, he said, but months of “education” and reading in a detention center brought him to his senses, he said.

“In my opinion, everyone who posts on Weibo must be cautious in their comments and actions, must think about their responsibilities,” he said.

But some on the Internet reacted with scorn to the condemnation of Xue in a country where corruption runs deep through the Communist Party and officials are often exposed by disgruntled mistresses.

If authorities checked officials’ assets as closely as they did Xue’s private life, one user posted, “corrupt officials in China would be long gone.” The post was later deleted, apparently by censors.

Several academics and media insiders declined to comment on the campaign, except to say that strict instructions to back it had come down from the top levels of the party. “I absolutely support this campaign; I’m not supposed to add anything more than that,” said one academic who spoke on the condition of anonymity for fear of official retribution.

Since Xi took power, journalists and micro-bloggers have faced greater censorship and scrutiny. Under the new campaign, editors of the main media houses were summoned for a meeting in recent days that urged a more intense crackdown.

“Let’s join hands to clean up the internet, create clear sky,” an article proclaimed on the Web sites of the Xinhua news agency Monday.

Part of the effort is aimed squarely at pornography: The “Cleaning the Web 2014” campaign will conduct thorough checks on Web sites, search engines and mobile application stores, Internet TV USB sticks and set-top boxes, the National Office Against Pornographic and Illegal Publications said Sunday.

Several Web sites have been closed this week for carrying homoerotic fiction, and several writers have been detained, according to local media.

A popular online video service provider also posted a notice Wednesday promising to remove all pirated and vulgar videos from its server and invest more than $15 million next year in copyrighted material.

“The dark current of pornographic information is still flowing on the Internet,” the People’s Daily warned in an editorial. It complained about illegal and foreign Web sites, pornographic marketing and obscenity posing as sex education. “Cracking down on Internet pornographic information matters to the physical and mental health of the youth,” the People’s Daily warned in an editorial. “It matters to promote our core socialist values,” the editorial said.

But the protection of socialist values also apparently involves a clampdown on criticism by journalists and fiction writers.

Several well-known Web sites carrying Internet fiction have been asked to do “thorough self-inspection,” according to reports online, and to delete any stories related to senior party officials and their families, as well as top military figures.

In one city in southern China alone, 21 journalists were found guilty of extortion last week in what authorities called their “iron fist response” to “fake news” and negative media coverage, according to a report Monday in the Yangcheng Evening News.

The journalists in Maoming were accused of having demanded money in return for not running negative news stories about local officials, teachers, entrepreneurs and others.

Maya Wang of Human Rights Watch in Hong Kong said journalists are routinely handed “red envelopes” stuffed with cash by the state in China in return for favorable coverage, establishing a “system of sanctioned corruption” across the journalistic profession. Those targeted by anti-extortion campaigns are often those “who have offended some official,” she said.

Liu Liu and Xu Yangjingjing contributed to this report.