SHANGHAI (NYTIMES) - As the number of coronavirus infections in China continues to surge without any sign of slowing down, the Communist government has clamped down on the news media and the Internet, signalling an effort to control the narrative about a crisis that has become a once-in-a-generation challenge for leaders in Beijing.

Chinese health officials said on Thursday (Feb 6) that 563 people had died from the virus, up from 490 people the day before, and that there were 28,018 confirmed cases of infection. Thousands more are being infected every day, and many Chinese fear that the virus' spread is not being adequately controlled.

With frustrations running high across the country, China's leaders appear to be strengthening information controls after a brief spell in which news organisations were able to report thoroughly on the crisis and many negative comments about the official response were left uncensored online.

In recent days, both state-run news media and more commercially minded outlets have been told to focus on positive stories about virus relief efforts, according to three people at Chinese news organisations who spoke on the condition of anonymity to discuss internal directives.

Internet platforms have removed a range of articles that suggest shortcomings in the Chinese government's response or are otherwise negative about the outbreak.

Local officials have also cracked down on what they call online "rumours" about the virus. China's public security ministry this week lauded such efforts, which have continued even after one person who was reprimanded for spreading rumours turned out to be a doctor sounding the alarm about early cases of the illness.

The Chinese government has shifted its strategy for information control in response to the changing nature of the public's discontent, said Associate Professor Fu King-wa, of the Journalism and Media Studies Centre at the University of Hong Kong.

In the early days of the crisis, online vitriol had largely been directed at the local authorities. Now, more of the anger is being aimed at higher-level leadership, and there seems to be more of it overall, he said.

Late last month, for instance, after The New England Journal Of Medicine published a research paper about early cases of the virus, Chinese Web users pounced on the fact that several of the authors worked for the Chinese Centre for Disease Control and Prevention, saying they should have been informing the public, not furthering their research careers.

"Now I understand," one person wrote on the social platform Weibo. "The CDC's purpose all along was to publish research papers."

"I'm so mad that I'm speechless," wrote another.

The researchers later said that all their information about the infections had already been made public before the paper was written.

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At this point, Prof Fu said, more censorship "wouldn't stop the public frustration".

The rapidly rising number of infections and deaths from the virus has put renewed pressure on the senior leadership in China. Hospitals near the centre of the epidemic have been overwhelmed, and people with flu-like symptoms have been turned away. Many cases have not been diagnosed because of a shortage of testing kits.

Still, the number of people in China who are recovering is rising, as well. And on Wednesday, a senior Chinese health expert attributed the large rise in the number of confirmed cases to the fact that hospitals had been able to diagnose the virus more quickly. The number of suspected cases has dropped for the same reason, the expert, Prof Li Xingwang, said at an official news briefing.

The new curbs on information appeared to have been set in motion earlier this week, when China's leader, Mr Xi Jinping, and other senior officials said at a meeting that they would "strengthen control over online media" as one of several measures to maintain social stability.

The leaders said that the government's propaganda efforts should focus on "vividly conveying the stirring achievements from the front lines of epidemic prevention" and "showing the Chinese people's unity and spirit of pulling together in difficult times", according to Xinhua, the official news agency.

After the meeting, a top official at China's central propaganda department told the state broadcaster CCTV that his department had dispatched more than 300 journalists to the epidemic's front lines in Wuhan and its surrounding province, Hubei.

The official, Mr Zhang Xiaoguo, said the department would make publicising the government's prevention-and-control campaign its "highest priority".

It was unclear whether the 300 journalists included those who were already reporting in Hubei or whether they would be new arrivals. It was also unclear what news organisations they would represent. The propaganda department did not respond to a fax requesting comment.

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Employees at Chinese news organisations this week described a mandatory change of tone in their stories and fresh orders to hew to the official line.

Journalists at the Xinhua news agency, for example, have been told to keep their coverage of the virus positive, according to internal instructions seen by The New York Times. They were ordered not to continue mentioning the fact that the World Health Organisation had declared a global health emergency and not to cover every infection discovered overseas.

"Only cover what needs to be covered," the instructions said.

Across the rest of China's news landscape, articles on a broad range of themes have been blocked or deleted online in recent days.

They include a report in the financial news magazine Caijing about deaths in Wuhan that might not have been counted in the official tally; a first-hand account of a funeral home in Wuhan; and even an interview with the head of a popular restaurant chain who said that he might be out of cash in a few months if the virus is not contained.