China has said a SARS-like virus outbreak which could spread across the country during Lunar New Year celebrations is "controllable" after reports of 17 new cases in the city of Wuhan.
In its first statement since the virus was detected, China's National Health Commission insisted the disease's source was unknown, but vowed to "step up monitoring" of any mutations during the festival period.
Millions of Chinese will be heading home to their families for the holiday, also called the Spring Festival, in the next few days.
The disease, also known as the coronavirus, is connected to Severe Acute Respiratory Syndrome (SARS), which killed nearly 650 people in China and Hong Kong during 2002 and 2003.
Of the 17 new cases in the central city of Wuhan, believed to be the epicentre of the outbreak and where 62 people are now affected, three were described as "severe".
The disease has also spread overseas, with two cases reported in Thailand, and one in Japan.
Two people have died so far, including a 69-year-old man in whom it caused pulmonary tuberculosis and damaged his organ functions.
Chinese authorities said they had begun "optimised" testing of cases across the city to identify those infected, and said they would begin "detection work towards suspected cases" as well as carrying out "sampling tests".
Scientists from the MRC Centre for Global Infectious Disease Analysis at Imperial College in London have warned that the number of cases in Wuhan is likely to be much higher than officially identified - closer to 1700.
China is yet to confirm whether the virus can be spread from one person to another, but Wuhan's health commission has said it "cannot be excluded".
China's centre for disease control sought to quash speculation about the disease at the weekend, with a leaflet dismissing "five big rumours". One included claims about the coronavirus spreading, which the disease control authority ruled out by saying that all cases were being treated in Wuhan.
Although there has been no official announcement of screening measures, Chen Xiexin, Wuhan's deputy mayor, said infrared thermometers had been installed at airports, railway stations and coach stations across the city. He said that passengers with a fever were being registered, given masks and taken to medical institutions.
Nearly 300,000 body temperature tests have been carried out, according to state broadcasters. Authorities in Hong Kong have also stepped up detection measures, including temperature checkpoints for travellers arriving from the Chinese mainland.
The US has said it will begin screening direct flights arriving from Wuhan at San Francisco airport and New York's JFK, as well as Los Angeles, where many flights connect.