China's daily Covid cases have hit a record high since the beginning of the pandemic, official data showed Thursday, as the country works to curb the spread with snap lockdowns, mass testing and travel restrictions.

China recorded a total of 31,444 domestic cases Wednesday, of which 27,517 were asymptomatic, the National Health Bureau said.

The numbers are relatively small when compared with China's vast population of 1.4 billion, AFP reported.

But under Beijing's strict zero-Covid policy, even tiny outbreaks can shut down entire cities and place contacts of infected patients into strict quarantine.

The unrelenting policy has caused fatigue and resentment among swathes of the population as the pandemic nears its third year, sparking sporadic protests and hitting productivity in the world's second-largest economy.

Wednesday's figures exceed the 29,317 domestic infections recorded in mid-April when megacity Shanghai was under lockdown, with residents struggling to buy food and access medical care.