BEIJING » Jing Yuechen, the founder of an Internet startup here in the Chinese capital, has no interest in overthrowing the Communist Party. But these days she finds herself cursing the nation’s smothering cyberpolice as she tries — and fails — to browse photo-sharing websites like Flickr and struggles to stay in touch with the Facebook friends she has made during trips to France, India and Singapore.

Gmail has become almost impossible to use here, and in recent weeks the authorities have gummed up Astrill, the software Jing and countless others depended on to circumvent the Internet restrictions that Western security analysts refer to as the Great Firewall.

By interfering with Astrill and several other popular virtual private networks, or VPNs, the government has complicated the lives of Chinese astronomers seeking the latest scientific data from abroad, graphic designers shopping for clip art on Shutterstock.com and students submitting online applications to U.S. universities.

"If it was legal to protest and throw rotten eggs on the street, I’d definitely be up for that," Jing, 25, said.

China has long had some of the world’s most onerous Internet restrictions. But until now, the authorities had effectively tolerated the proliferation of VPNs as a lifeline for millions of people, from archaeologists to foreign investors, who rely heavily on less-fettered access to the Internet.

But earlier this week, after a number of VPN companies, including StrongVPN and Golden Frog, complained that the Chinese government had disrupted their services with unprecedented sophistication, a senior official for the first time acknowledged its hand in the attacks and implicitly promised more of the same.

The move to disable some of the most widely used VPNs has provoked a torrent of outrage among video artists, tech entrepreneurs and university professors who complain that in its quest for so-called "Internet sovereignty" — Beijing’s euphemism for online filtering — the Communist Party is stifling the innovation and productivity needed to revive the Chinese economy at a time of slowing growth.

"I need to stay tuned into the rest of the world," said Henry Yang, 25, the international news editor of a state-owned media company who uses Facebook to follow broadcasters like Diane Sawyer, Ann Curry and Anderson Cooper. "I feel like we’re like frogs being slowly boiled in a pot."

Multinational companies are also alarmed by the growing online constraints. Especially worrisome, they say, are new regulations that would force foreign tech and telecom companies to give the government "back doors" to their hardware and software and require them to store data within China’s borders.

Like their Chinese counterparts, Western business owners have been complaining about their inability to gain access to many Google services since the summer. A few weeks ago, the government cut off the ability to receive Gmail on smartphones through third-party email services like Apple Mail or Microsoft Outlook.

The recent disabling of several widely used VPNs has made it difficult for company employees to use collaborative programs like Google Docs, although some people have found workarounds — for the time being.

"One unfortunate result of excessive control over email and Internet traffic is the slowing down of legitimate commerce, and that is not something in China’s best interest," said James Zimmerman, chairman of the American Chamber of Commerce in China. "In order to attract and promote world-class commercial enterprises, the government needs to encourage the use of the Internet as a crucial medium for the sharing of information and ideas to promote economic growth and development."

Chinese authorities have long had the ability to interfere with VPNs, but their interest in disrupting such programs has mounted alongside the government’s drive for so-called cyber-sovereignty, especially since President Xi Jinping came to power two years ago. Lu Wei, the propaganda official Xi appointed as Internet czar, has been unapologetic in promoting the notion that China has the right to block a wide array of online content.

A co-founder of Greatfire.org, which tracks online censorship in China, suggested the government had decided that soaring VPN use among ordinary Chinese warranted a more aggressive attack on such tunneling software.

"This is just a further, logical step," said the co-founder, who requested anonymity to avoid government scrutiny. "The authorities are hellbent on establishing cyber-sovereignty in China. If you look at what has taken place since last summer it is quite astounding."

Government officials have denied any role in blocking Google and they have dismissed accusations that Chinese authorities were behind a "man-in-the-middle" attack on Outlook two weeks ago as well as earlier hacking incidents here involving Yahoo and Apple.

But such claims have by and large fallen on deaf ears, especially given Beijing’s strident campaign against the "hostile foreign forces" it says are seeking to undermine the country though the Internet.

On Tuesday, however, a senior official at the Ministry of Industry and Information Technology acknowledged that the government was targeting VPNs to foster the "healthy development" of the nation’s Internet and he announced that such software was essentially illegal in China. "The country needs new methods to tackle new problems," Wen Ku, a director at the ministry, told a news conference, according to People’s Daily.

In recent weeks, a number of Chinese academics have gone online to express their frustrations, particularly over their inability to reach Google Scholar, a database that provides access to millions of scholarly papers from around the world.

"It’s like we’re living in the Middle Ages," Zhang Qian, a naval historian, complained on the microblog service Sina Weibo.

In an essay that has been circulating on social media, one biologist described how the unending scramble to find ways around website blockages was sapping colleagues’ energy.

"It’s completely ridiculous," he wrote of the wasted hours spent researching and downloading VPN software that works. "For a nation that professes to respect science, and wants to promote scientific learning, such barriers suggest little respect for the people actually engaged in science."

It is not just scientists who have come to depend on an unabridged Internet for their work. Cheng Qingsong, a prominent film critic, complained that it was more and more difficult to stream foreign movies. Andrew Wang, a professor of translation at Beijing Language and Culture University, worried that his students would be unable carry out assignments that require them to watch English-language videos on YouTube, which has long been blocked here.

"It’s hurting everyone," he said. "I can afford to spend $10 a month on a VPN that works, but for my students, that’s a lot of money."

The vast majority of Chinese Internet users, especially those not fluent in English and other foreign languages, have little interest in vaulting the digital firewall. But those who require access to an unfiltered Internet are the very people Beijing has been counting on to transform the nation’s low-end manufacturing economy into one fueled by entrepreneurial innovation.

Illustrating of such contradictions, the central government this week announced a series of programs that seek to lure more international business talent by easing visa requirements and through other incentives.

"We have to focus on the nation’s strategic goals and attract high-level talent to start innovative businesses in China," said Zhang Jianguo, director of the State Administration of Foreign Experts Affairs, who bemoaned the nation’s shortage of scientists and tech entrepreneurs.

Those goals, however, will not be helped by the latest assaults on Internet access, critics say. Avery Goldstein, a professor of contemporary Chinese studies at the University of Pennsylvania, said the growing online constraints would not only dissuade expatriates from relocating here, but could also compel ambitious young Chinese studying abroad to seek job opportunities elsewhere.

"If they aren’t able to get the information to do their jobs, the best of the best might simply decide not to go home," he said.

For those who have already returned to China and who crave membership in an increasingly globalized world, the prospect of making do with a circumscribed Internet is dispiriting. Coupled with the unrelenting air pollution and the crackdown on political dissent, a number of Chinese said the government’s effort to block VPNs could push them over the edge.

"It’s as if we’re shutting down half our brains," said Chin-Chin Wu, an artist who spent almost a decade in Paris and who relies on the Internet to promote her work overseas. "I think that the day that information from the outside world becomes completely inaccessible in China, a lot of people will choose to leave."

© 2015 The New York Times Company