Around 20 million people are now confined to their homes in China after a third city entered a lockdown over two Omicron Covid cases.
Anyang - which has around 5.5 million residents - confirmed two cases of Omicron on Monday, and they are believed to be linked to two other cases found on Saturday in Tianjin.
Another 13 million people in lockdown in the city of Xi’an and 1.1 million in Yuzhou. Both have cases of the Delta variant, but no Omicron cases.
Residents in Anyang are not allowed to leave their homes. Non-essential vehicles are banned from roads. And only shops selling essentials can open.
China has stepped up its strict zero-Covid policy ahead of the 2022 Winter Olympics in Beijing, which begins on February 4.
The two Omicron cases in Anyang appear to be the first time Omicron has spread in China beyond people who arrived from abroad and their immediate contacts.
China’s largest Covid outbreak in recent months is in Xi'an - where about 2,000 people have been infected.
Restrictions are also imposed on the port city of Tianjin, about an hour from Beijing.
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Huang Chun, a games official responsible for disease control, said: “If the mass cluster transmission happens, it will impact the games and the schedule for sure.
“The worst scenario, if it happens, is independent of man’s will, so we leave our options open.”
Mass testing is being enforced in all areas where there are outbreaks.
Hong Kong, a special administrative region, also announced that kindergartens and primary schools had to close after infections were reported among pupils.
Schools have to close by Friday until at least the Lunar New Year in the first week of February.
The city has recently imposed tighter restrictions after the local transmissions of the Omicron variant.
Restaurants have to close dine-services from 6pm. Gyms, pools, cinemas and salons are shut. And flights from eight countries, including the UK, are banned for two weeks from January 8.