After the discovery of a few dozen corona infections in Beijing, all 3.5 million residents of the largest district of Chaoyang have had to be tested in three rounds every two days since Monday.

The fear of strict curfews in the Chinese capital caused panic buying and empty shelves in supermarkets.

Authorities warned that the virus had been spreading undetected in the metropolis of 21 million for a week, so more cases are likely to be discovered.

Whether a lockdown is imposed on all or parts of Beijing depends on the spread of the virus, an expert from the national health department told the party-affiliated newspaper Global Times.

"When the results of the tests in Chaoyang and other parts come out, it will give us a better picture of the overall epidemic situation in Beijing," the senior official said.

"Further measures will follow accordingly." The foreign embassies are located in the Chaoyang District and most foreigners live in Beijing.

After individual blocks of flats had already been sealed off due to infections at the weekend, the authorities also imposed a lockdown on several neighborhoods in the Chaoyang District to the east on Monday.

Residents are not allowed to leave the area for the time being.

Restaurants and entertainment venues have been closed.

Lessons from the Corona outbreak in Shanghai

With the quick approach, the already particularly well-protected capital also wants to learn lessons from the corona outbreak in Shanghai and other provinces, it said.

There was criticism of the initially slow approach in the eastern Chinese port city, where the situation has still not been under control for almost a month despite extensive curfews.

There are also complaints of insufficient food supplies and poor medical care.

From Tuesday, all 26 million residents of Shanghai will also be tested again.

China is pursuing a zero-Covid strategy, which will be put to the test with the arrival of the fast-spreading Omicron variant.

Shanghai is at the center of the largest corona wave in China since the pandemic began a good two years ago.

The port metropolis reported the highest number of outbreaks with 51 deaths on Sunday in connection with Covid-19.

By then, 87 deaths had already been reported.

According to the Health Commission, most of the 23,000 new infections nationwide were detected on Sunday;

most were asymptomatic.