“We have declared a people’s war … [and] are fully confident and capable of fighting the epidemic. The long-term trend of China’s economic development will not change.”

Trump said on Twitter on Friday that he had had a “very good conversation” with Xi and that he was confident China’s efforts to contain the coronavirus outbreak would be successful.

“He is strong, sharp and powerfully focused on leading the counterattack on the Coronavirus,” the tweet said.

“He feels they are doing very well, even building hospitals in a matter of only days. Nothing is easy, but he will be successful, especially as the weather starts to warm & the virus hopefully becomes weaker, and then gone.

“Great discipline is taking place in China, as President Xi strongly leads what will be a very successful operation. We are working closely with China to help!”

The coronavirus outbreak, which began in the central China city of Wuhan, has infected more than 31,000 people and killed over 630 in mainland China. It had also spread to about two dozen other countries and territories.

Despite the growing number of infections and fatalities, WHO director general Tedros Adhanom Ghebreyesus said that measures that interfered with transport and trade could actually harm global efforts to contain the virus.

After Italy banned all flights to and from China earlier this week, China’s vice-minister of foreign affairs Qin Gang met Italy’s ambassador to China Luca Ferrari in Beijing on Thursday.

“Italy’s decision to stop flights without contacting China in advance caused great inconvenience to citizens of both countries. Many Chinese are still stranded in Italy,” the foreign ministry said on its website on Friday.

The statement went on to say that Rome was willing to resume some flights between the two countries, although Italy’s health ministry said on its website that the restriction remained in place.

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While Chinese airlines have been forced to limit their domestic routes as part of the effort to contain the outbreak, the Civil Aviation Administration of China on Tuesday urged them to maintain their international routes.

“In order to meet the needs of passengers in and out of the country and the international transport of supplies during this special period … airlines [are required to] … continue transport to nations that have not imposed travel restrictions.”

Xie Feng, Beijing’s top diplomat in Hong Kong, on Friday accused some nations of overreacting to the coronavirus outbreak.

“We hope countries will respect the professional and authoritative advice of the WHO, maintain normal economic cooperation, trade and people-to-people exchanges … and stop overreacting and fearmongering,” he told a press conference.

Zi Yang, a senior analyst with the China Programme at the S. Rajaratnam School of International Studies (RSIS) at Singapore’s Nanyang Technological University, said the reaction of China’s diplomats came as no surprise.

“The reaction was expected in some ways,” he said. “Under Xi, diplomats have been more aggressive.”

It was possible that Beijing thought the move by the US would trigger a global chain reaction that would hurt China economically, he said, adding that the economic outlook for China was “not rosy at all”.

S&P Global Ratings on Friday lowered its economic growth forecast for China in 2020 to 5 per cent, from 5.7 per cent before the coronavirus outbreak.

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Despite Xi’s claims about how well Beijing was dealing with the crisis, Yang said in a recent report, titled “China’s Response to Coronavirus Outbreak”, that there had been “severe under-reporting” of the number of infections and that some countries doubted the official figures.

“Information control has been tight,” he said. “Chinese authorities issued warnings to those spreading online rumours regarding the disease and police questioned individuals about this issue.”

Overall, Beijing’s efforts at containment had been “proactive but opaque”, he said.

Zhang Baohui, director of the Centre for Asian Pacific Studies at Lingnan University in Hong Kong, said Beijing was worried about foreign countries imposing travel bans as it would undermine its efforts to portray itself as a “responsible great power”.

China was particularly sensitive to moves by the US, he said, as these might accelerate the decoupling of the two countries and “facilitate the agenda of the China hawks” in America.

“If the virus is not contained quickly, its impact on China’s economy will not only affect its growth rates but also motivate foreign companies to relocate to other countries,” Zhang said. “This should be a concern to China.”

Despite years of reform and restructuring, China remains an export-driven economy so a decoupling from the US would have a huge economic impact.

Rajeev Ranjan Chaturvedy, a visiting fellow at RSIS, said China’s “sensitive” reaction to foreign nations’ moves was largely due to a fear of its legitimacy being undermined.

The coronavirus outbreak also “underlines the failure” of the Chinese government to deal with the situation, he said.

“It creates a lot of negativity about the Chinese political system, particularly the way the problem was handled initially.”