The death toll from the new coronavirus in China climbed to six Tuesday as new cases of the mysterious flu-like illness surged beyond 300, raising concerns of a major outbreak during the Lunar New Year travel rush.

Anxiety grew both at home and abroad after Zhong Nanshan, chief of the National Health Commission, confirmed fears late Monday that the virus can spread from human to human.

Officials have confirmed more than 300 cases in China, mostly in the central city of Wuhan, a major transportation hub, where the virus may have originated at a seafood market.

There have been six deaths in that city, Mayor Zhou Xianwang told Chinese state media Tuesday.

But the virus has been spreading around other parts of China, including more than 20 cases in the capital of Beijing, Shanghai, Guangdong province in the south and Zhejiang in the east. Fifteen medical workers are among those infected.

Abroad, Thailand has reported two cases and South Korea one, all involving Chinese travelers from Wuhan. Japan and Taiwan also confirmed one case each, both nationals who had been to that city.

“Information about newly reported infections suggest there may now be sustained human-to-human transmission,” said Takeshi Kasai, the World Health Organization’s regional director for the western Pacific, Reuters reported.

So far, the WHO has not recommended trade or travel restrictions but such measures could be addressed during a meeting Wednesday.

In the US, officials with the Centers for Disease Control and Prevention are taking temperatures of passengers at New York’s JFK and the Los Angeles and San Francisco international airports who arrive from Wuhan.

Airports in Australia, Japan and South Korea also have begun screening passengers from the city, where officials have been using infrared thermometers to screen passengers since Jan. 14.

Images of long lines of people lining up to buy face masks were circulating widely on Chinese social media during the Lunar New Year, a major holiday for Chinese, many of whom travel to join family or have a foreign holiday.

The Chinese government has estimated people will make about 3 billion trips during the travel season, but some social media users have said they may stay home amid concern about the virus.

Some online vendors were limiting sales of masks and hand sanitizers as demand skyrocketed. Several online retailers were sold out of masks, which were being sold for more than 10 times their original price.

Users of the popular Weibo social media platform urged people to wash their hands and stay home. Initial symptoms of the new coronavirus include fever, cough, chest tightness and shortness of breath.

The coronavirus has caused alarm because of its genetic similarities to SARS, or severe acute respiratory syndrome, which first infected people in southern China in late 2002 and spread to dozens of countries, killing nearly 800.

The Chinese government announced it was classifying the new outbreak in the same category as SARS, meaning mandatory isolation for those diagnosed with the disease and the potential to implement quarantine measures on travel.

China initially tried to conceal the severity of the SARS epidemic, but its cover-up was exposed by a high-ranking physician.

With Post wires