Chinese cities battle Covid as Olympics loom

China is battling coronavirus outbreaks in several cities, testing the country's strict "zero-Covid" strategy just weeks before Beijing hosts the Winter Olympics.

Here's a rundown of the measures in place in key areas of the world's most populous nation.

Fears are growing about China's largest domestic Omicron cluster to date in the northern port city of Tianjin, where two confirmed cases of the highly transmissible variant were discovered over the weekend.

Local virus prevention official Zhang Ying said Saturday that the strain of virus identified had been transmitting for "at least three generations" -- indicating weeks of earlier spread -- with the source unclear.

Thirty-three new transmissions were reported in the city on Wednesday, as authorities launched a second round of mass testing for the 14 million population.

Local officials said Tuesday that all 80 patients reported up to that point had received at least two doses of a vaccine.

"We are highly concerned about whether the virus has spilled over to areas outside Tianjin... especially Beijing," Zhang said in a Monday interview with state broadcaster CCTV, adding that its rapid transmission has brought "unprecedented challenges".

Residents cannot leave the city without official permission, while an entire district and two nearby townships were locked down.

Buses and flights out of the city were cancelled Tuesday, and schools and university campuses have been closed.

While small, the Tianjin outbreak is noteworthy because of the city's proximity to Beijing just 150 kilometres (90 miles) away.

Authorities have stepped up controls over transport links to Beijing, with trains cancelled and highway checkpoints installed.

The historic city of 13 million people is in its third week of a strict lockdown as it races to stamp out a 2,000-case outbreak, one of the largest in China for months.

Residents may not leave their homes or travel out of the city, famed for its Terracotta Warriors.

Local authorities have come under fire for their handling of a lockdown that has included supply issues and medical tragedies.

A top health official made a public apology last week over the miscarriage of an eight-month pregnant woman, after a viral video of her being refused entry to a hospital without a Covid test prompted outrage on social media.

Several cities in the central province of Henan -- which lies near Xi'an -- have strengthened virus controls in response to hundreds of new infections since late December.

The province on Wednesday reported 87 new local cases. It is not clear how many of these are Omicron cases.

Provincial capital Zhengzhou has imposed a partial lockdown and ordered its nearly 13 million residents to get tested.

Last week, one million people in Yuzhou city were put under stay-at-home orders.

On Monday, the city of Anyang reported 18 local cases, including two Omicron infections linked to the Tianjin cluster.