Dozens of people have taken part in a rare protest in the southern Chinese tech hub of Shenzhen, social media footage shows, after officials announced a snap lockdown over a handful of Covid cases.

The megacity of more than 18 million people reported just 10 infections on Tuesday, but officials have still ordered residents in three districts to stay home as China sticks to its strict zero-Covid policy.

Officials are also under pressure to snuff out outbreaks quickly ahead of a key political meeting in Beijing next month.

Videos circulating on China's Twitter-like platform Weibo and Instagram since Monday — verified by AFP — show dozens chanting "lift the Covid lockdown" as rows of police in medical protective gear look on.

In one clip a woman shouts: "Police are hitting people."

The protest took place in Shawei, a neighborhood in Futian district where the city government is based, AFP confirmed.

Shawei's subway station was shut down from 10 pm (1400 GMT) on Monday until further notice "as part of pandemic prevention and control", the city's metro operator said in a statement.

At least 14 "high-risk areas" across three districts — Futian, Luohu, and Longgang — were under lockdown on Tuesday, with residents forced to stay in their homes, health officials said without offering details on the number of people affected.

Another 15 neighborhoods are marked as medium risk, with residents only allowed to walk inside their housing compounds.

Shenzhen, a sprawling tech hub that neighbors Hong Kong, had just emerged from strict Covid restrictions that saw schools and entertainment venues closed for weeks in early September.

The city only allows residents to board public transport, enter a restaurant, or access public services including hospitals if they have a negative PCR Covid test taken within 24 hours.

Hong Kong scrapped its mandatory hotel quarantine requirement for arrivals on Monday after the strict virus rules threatened the city's status as a key financial hub.

China is the only major economy still holding fast to a zero-Covid strategy, with its borders virtually closed since the virus first emerged in late 2019.

Swift lockdowns, long quarantines, and mass testing have been a drag on its economy.

Earlier this year, a grueling two-month lockdown in Shanghai — the world's third most populous city with over 25 million residents — was marked by food shortages, deaths due to lack of access to medical care, and scattered protests.

In August, more than 80,000 tourists were stranded in the resort city of Sanya after a Covid flare-up.

Tourists took to the streets shouting for local leaders to meet with them.