China reported its biggest single-day jump in novel coronavirus deaths on Thursday, as confirmation that three Japanese people evacuated from Wuhan, the outbreak’s epicentre, were infected deepened fears about a global contagion, and more countries announced plans to bring their citizens home from the hard-hit city.

The World Health Organization (WHO), which initially downplayed the severity of a disease that has now killed 170 people across the country, warned all governments to be “on alert” and will meet on Thursday to discuss whether to declare a global health emergency.

China has taken extraordinary steps to try and curb the spread of the virus, effectively sealing off Wuhan and the surrounding province of Hubei an area that is home to more than 50 million people. But the measures have yet to pay dividends, with the government reporting 38 new deaths in the 24 hours to Thursday, the highest one-day total. All but one were in Hubei.

The number of confirmed new cases also grew steadily to 7,711, the National Health Commission said. A further 81,000 people were under observation for possible infection.

The infection is believed to have started in Wuhan, and spread as people began travelling for the Lunar New Year or Spring Festival, the country’s busiest and most important holiday season. With a case confirmed in Tibet, it has now spread to every corner of the country.

Japan reported additional infections after three citizens among more than 200 on an evacuation flight from Wuhan on Wednesday tested positive for the infection. Two had shown no sign of the illness, adding to anxieties after two previous cases had already been confirmed in patients who had not even travelled to China.

“We are in a truly new situation,” Health Minister Katsunobu Kato told parliament.

WHO’s Emergency Committee will meet in Geneva to decide whether to declare an emergency, which could lead to travel or trade barriers.

“The whole world needs to take action,” Michael Ryan, head of the WHO Health Emergencies Programme, told reporters in Geneva.