Live updates: follow the latest news on Covid-19 variant Omicron
The northern coastal city of Tianjin began testing its population of about 14 million on Sunday after at least two local cases of the highly transmissible Omicron coronavirus variant were detected, China's state media reported.
Residents in four districts would be tested over the next 24 hours while other districts would be tested the next day, the Tianjin government said.
Residents will get the green health code necessary to travel once they receive a negative result, it said.
The city advised residents not to leave for unnecessary reasons, the government said late on Saturday. So far, no full lockdown order has been given.
The Tianjin outbreak poses risks to Beijing and the coming Winter Olympics. Large number of commuters work and live in the two cities, the state-owned Global Times reported, citing an unidentified immunologist.
Commuters to Tianjin from Beijing have been asked to stay away, the Xinhua news agency reported.
The news comes after local transmission of the Omicron variant was found in the southern city of Guangzhou, according to a national health official in December, although the number of cases was not disclosed.
China reported 165 confirmed coronavirus cases for January 8, up from 159 a day earlier, its health authority said on Sunday.
Of the new infections, 92 were locally transmitted, according to a statement by the National Health Commission. This was up from 95 a day earlier.
Most of the new local cases were in Henan and Shaanxi provinces.
China reported 46 new asymptomatic cases, which it classifies separately from confirmed cases, compared with 52 a day earlier.
There were no new fatalities, leaving the death toll at 4,636. Mainland China had 103,619 confirmed cases as of Jan 8.
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