Imported coronavirus cases in China outnumbered cases of location transmission for the fifth straight day as infected travellers passed through major Chinese transportation hubs in Beijing, Shanghai, Guangzhou and Shenzhen.
Mainland China had 13 new confirmed cases of coronavirus infections on Tuesday, the country's National Health Commission said, down from 21 cases a day earlier. Of the new cases, 12 involved infected travellers arriving from abroad.
In contrast to the current wave of imported cases, mainland China had only one case of locally transmitted infection on Tuesday, in Wuhan, capital of central Hubei province where the flu-like disease surfaced in humans late last year.
The capital Beijing accounted for three of the imported new cases, down from nine a day earlier. Shanghai had three new cases, unchanged from the day before.
Imported cases in southern Guangdong province rose to five from three, due to people arriving from Thailand, Britain and the Netherlands. One infection emerged in Sichuan in southwest China.
The overall number of imported cases of the virus in mainland China reached 155 as of Tuesday, up 12 from a day earlier.
That brings the total number of confirmed cases in mainland China so far to 80,894, the health authority said in a statement on Wednesday.
Though imported cases are on the rise, local transmissions remain a risk, with some patients showing few symptoms and travelling around undetected for days.
Earlier this month, a 30-year old policeman from central China's Henan province flew back to Beijing after a week-long trip to Italy before returning by train to the provincial capital of Zhengzhou.
He wasn't diagnosed until March 11, after he had returned to work for several days. At least 11 cities in China have tracked down locals who were exposed to him during his journey.
The death toll from the outbreak in mainland China had reached 3,237 as of the end of Tuesday, up by 11 from the previous day.
In Hubei, the epicentre of the outbreak in China, there were 11 new deaths, with Wuhan accounting for 10 of the fatalities.
While the rest of Hubei had zero new infection for almost two weeks, Wuhan reported new infections through outpatient diagnosis for the fifth day, in a worrying sign of continued local transmissions despite draconian social distancing and quarantine measures for nearly two months.
"The new infected patients and their family members have gone out and about in their local community during this period of staying at home, which does not exclude the possibility of community infection," the Wuhan coronavirus task force said in a text message sent to some Wuhan residents late on Tuesday.
The Wuhan Health Authorities said the new case on Tuesday was a manager at a vegetable market, and was suspected of having contracted the virus through exposure to the market.
"What we are most worried about is that there is an undetected source of the coronavirus, which will be a loophole leading to the resurgence of the pneumonia," a Wuhan-based doctor was cited by the People's Daily as saying.
Wuhan remains the only city in Hubei still designated as "high-risk" and subject to strict travel bans, as authorities are keen to get other parts of the province back to work.
Hubei has now classified 71 of its 75 districts to be "low-risk". The city of Ezhou, one of four still classified as "medium-risk", said on Wednesday that it would let non-residents leave the city to return to work in other regions, as long as they were not travelling to Beijing.