HONG KONG — The State Department issued a travel advisory urging Americans not to visit China, the highest level of caution that is in place against only a handful of countries including Iraq and Afghanistan, as the numbers of those infected by the deadly coronavirus continued to soar.

Other countries ramped up restrictions, too, as officials tried to contain the fast-spreading outbreak. Singapore on Friday banned all Chinese nationals from entering or transiting through the city-state, as well as any travelers who have been in mainland China in the past two weeks. Japan urged citizens to defer nonessential trips to China, widening earlier advice.

The U.S. travel advisory, analysts say, represents a strong reaction from Washington amid rivalry with Beijing and pressure from the Trump administration for American businesses to shift production back home. The step is likely to have substantial implications for the Chinese economy, even though the warning is not mandatory for U.S. travelers to observe.

In addition, the tightening restrictions on Chinese travelers is set to deliver a major hit to economies of Asia that rely on billions of dollars in spending by Chinese tourists.

The number of people in China infected with the new coronavirus has increased tenfold in just a week to almost 10,000, according to official statistics released Friday. That is more than the worldwide total of those infected by severe acute respiratory syndrome, or SARS, which devastated China and other parts of Asia in 2003. The country has over 15,000 suspected cases, with 213 recorded deaths.

The U.S. government is arranging more flights next week to evacuate Americans from Wuhan, capital of Hubei province and the epicenter of the outbreak.

But James Zimmerman, partner in the Beijing office of law firm Perkins Coie LLP and former chairman of the American Chamber of Commerce in China, said in light of the departure arrangement, the State Department’s travel warning appeared “extreme.”

It is “premature and suspect, and overreacting at best,” he said Friday. “The advisory is a clear reflection of how fear and a lack of trustworthy information can be an insidious combination.”

The advisory followed the World Health Organization’s declaration of the outbreak as a global health emergency — a move that pressured China to ramp up measures to contain the spread of the pathogen and to be more transparent about cases.

In a tweet, Secretary of State Mike Pompeo noted the WHO advisory as the basis for the new travel warning. The advisory added that Americans in China “should consider departing using commercial means,” and that government staff should defer nonessential travel to the country.

Already, the fallout has been significant for Chinese travelers globally. Dozens of airlines have suspended flights to the country and many companies have urged their staff to stay away. From Italy to the Philippines, hotels and ports have been turning away Chinese citizens over fears that they may be infected.

The response at times has morphed into outright racism. In France, the hashtag #JeNeSuisPasUnVirus — “I am not a virus” — began trending, with those of Asian descent sharing their experiences of racism after a newspaper used the headline “Yellow Alert” to describe the outbreak.

Restaurants in South Korea have put up signs turning away Chinese clients. A student in Britain wrote in the Guardian that commuters have avoided sitting next to him because of his ethnicity. And after 7,000 people were held on a cruise ship in an Italian port over unfounded fears that two of its Chinese passengers were infected with the virus, officials have warned of latent and widespread racism against the Chinese community.

The outbreak, meanwhile, continues to spread. Britain on Friday confirmed the first two cases of coronavirus in England. “We have been preparing for U.K. cases of novel coronavirus and we have robust infection control measures in place to respond immediately,” chief medical officer Chris Whitty said.

In South Korea, health officials reported an 11th case. Earlier Friday, 368 South Korean evacuees from Wuhan arrived home on a government-chartered flight. They were screened for symptoms, with 18 taken to the hospital and the remainder placed in quarantine.

Germany and India, which have each confirmed cases of coronavirus, were preparing to evacuate their citizens in Wuhan by plane. Over 350 names featured on a list drawn up by Indian officials, while Germany was planning to retrieve about 100 people.

Elsewhere, Mongolia extended the closure of its border crossings with China until March 2 and said it would not allow Chinese citizens to enter the country. Pakistan said it was halting flights to and from China with immediate effect.

In Hong Kong, officials said they were shuttering schools until March, while banks announced plans to close branches. Still, the city’s government continued to resist calls to close the border with China.

At a briefing late Friday, leader Carrie Lam defended that decision, citing advice from international experts.

“I really don’t think a complete close of the border control points is the right answer through the situation that we are facing,” Lam said. “It is at least not in line with the very scientific-based and knowledge-based advice given to us as early as this morning by the World Health Organization and its panel of experts.”

People stood in line for hours again on Friday hoping to obtain face masks and hand sanitizer, which have been in severely limited supply, fueling anger at the government over its preparedness. Hong Kong officials say they are undertaking a worldwide search to procure more masks for residents.

Chinese authorities, meanwhile, were preparing to send charter flights to repatriate citizens from Wuhan who had left China before travel advisories were in place, citing “practical difficulties” they had encountered abroad.

In announcing the health emergency in Geneva on Thursday, WHO chief Tedros Adhanom Ghebreyesus praised China for the speed with which it identified the virus and sequenced its genome, calling the action “impressive and beyond words” and congratulating the country for “extraordinary measures” to control the outbreak.

Yet cracks have appeared in China’s tightly controlled public realm. On social media, citizens — fearful, bored and confined indoors — have criticized the Communist Party’s response. In a post on the microblogging site Weibo about the WHO’s declaration, one user questioned why hospitals in Wuhan had run out of supplies, and asked why the Chinese government had not publicized the disease when officials discovered it back in December.

“I have donated money for the front-line medical staff in Wuhan, but not to those corrupted officials with black hearts!” the user wrote.

Mindful of the political danger, China dismissed a public health official — her departure publicized by state mouthpieces in a rare, officially sanctioned show of accountability. Tang Zhihong, the health commission head of Huanggang, a city in Hubei province with the second-largest number of cases after Wuhan, was interviewed by a state broadcaster and fumbled her answers on the city’s response to the crisis. She could not state the number of available hotel beds in her city, nor its capacity to test for the virus.

After the clip was viewed some 40 million times, Tang was dismissed on Thursday night, becoming the first Chinese official to lose her job over the crisis. Her removal was carried in English by the Communist Party’s Global Times newspaper, which described her as “bumbling.”

Others criticized what they saw as an opportunity for the West to further weaken China amid increasing strategic rivalry and a trade dispute with the United States.

Commerce Secretary Wilbur Ross, speaking on Fox Business on Thursday, said the coronavirus could “help” to bring jobs to the United States because companies would be moving operations away from affected areas.

“I think it will help to accelerate the return of jobs to North America, some to [the] U.S., probably some to Mexico as well,” Ross said.

Simon Denyer in Tokyo, Tiffany Liang, David Crawshaw and Timothy McLaughlin in Hong Kong, Niha Masih in New Delhi and Min Joo Kim in Seoul contributed to this report.