The number of people infected with a new virus in China tripled over the weekend, with the outbreak spreading from Wuhan to other major cities.
Wuhan reported 136 new cases of the respiratory illness. The capital Beijing reported two cases, while Shenzhen confirmed one.
Total known infections now exceed 200, and three people have died.
The sharp uptick in cases comes as millions of Chinese prepare to travel for the Lunar New Year holidays.
Health officials have identified the infection, which first appeared in Wuhan in December, as being a strain of coronavirus. They say it has led to an outbreak of viral pneumonia, but much about it remains unknown.
Although the outbreak is believed to have originated from a market, officials and scientists are yet to determine exactly how it has been spreading.
South Korea reported its first confirmed case of the virus on Monday, following two in Thailand and one in Japan.
The outbreak has revived memories of the Sars virus – also a coronavirus – that killed 774 people in the early 2000s across dozens of countries, mostly in Asia. Analysis of the genetic code of the new virus shows it is more closely related to Sars than any other human coronavirus.
READ ALSO: New Chinese Virus ‘Will Have Infected Hundreds’-British Scientists
Experts in the UK told the BBC the number of people infected could still be far greater than official figures suggest, with estimates closer to 1,700.
Authorities in Wuhan, a central Chinese city of 11 million that has been at the heart of the outbreak, on Monday said 136 new cases had been confirmed over the weekend, with a third person dying of the virus.
There had previously been only 62 confirmed cases in the city.
As of late Sunday, officials said 170 people in Wuhan were still being treated in hospital, including nine in critical condition.
Health officials in Beijing’s Daxing district meanwhile said two people who had travelled to Wuhan were treated for pneumonia linked to the virus.
In Shenzhen, a major tech hub close to Hong Kong, officials said a 66-year-old man showed symptoms of the virus following a trip to visit relatives in Wuhan. Eight others in Shenzhen have been quarantined and are under observation to determine if they have the virus.
Four cases have been confirmed abroad – all of them involving people who are either from Wuhan or have visited the city.
In South Korea, the Korea Centers for Disease Control and Prevention said a 35-year-old Chinese woman was suffering from a fever and respiratory problems after travelling there from Wuhan. She was put into isolation and treated at a local hospital.
The World Health Organization said it was currently not recommending restrictions on travel or trade, but was providing guidance to countries preparing for any outbreak.
