This is Vietnam's ninth infection case of new coronavirus that has killed 426 people as of Tuesday morning.

The man, whose name has not been revealed, is being quarantined at the National Hospital for Tropical Diseases in Hanoi's Dong Anh District. His conditions are stable, doctors said.

He was among a group of eight workers returning from work training in Wuhan on January 17.

Four of them had tested positive for the nCoV and three are under treatment. The other, a native in Thanh Hoa Province, was discharged from the provincial general hospital on Monday after doctors declared her free of the new coronavirus.

The workers were employees of Japan-based Nihon Plast Company Limited. They were sent for work training in Wuhan City in Hubei Province two months ago. They returned to Vietnam on a Southern China Airlines flight (CZ8315).

They were picked up by the company car at Hanoi's Noi Bai Airport and attended a company meeting in Thien Ke Commune, Binh Son District, Vinh Phuc Province, about 18 km from the airport.

Other confirmed cases in Vietnam are a Vietnamese-American who transited in Wuhan en route to Vietnam, two Chinese nationals, and a hotel receptionist who caught the coronavirus infection from the two Chinese, who have also recovered.

Vietnam's government declared the novel coronavirus an epidemic on Saturday. The country has reported 304 suspected cases with symptoms like high fever and coughing, including some people who had visited infected areas in China, as of Monday. Of them, 214 have tested negative for the virus and 90 are in quarantine pending test results.

The death toll from the epidemic has reached 426, with 425 dying in China and one in the Philippines.