Beijing will amp up its Covid-19 restrictions with additional testing requirements, officials announced on Saturday, as the start of the Labour Day holiday was muted by creeping infections in the capital.

The five-day break is typically one of the mainland's busiest travel periods, but the country's worst Covid resurgence since early in the pandemic is likely to keep people home.

Faced with the highly transmissible Omicron variant, Chinese officials have quashed virus clusters through mass testing and lockdowns.

Beijing announced it would further restrict access to public spaces after the holiday period.

Starting May 5, a negative Covid test taken within the past week will be needed to enter "all kinds of public areas and to take public transport", according to a notice on the city's official WeChat page.

For activities such as sporting events and group travel, participants will also need to show a negative Covid test taken within 48 hours, along with proof of "full vaccination", according to the new rules.

The capital will make Covid testing free for residents starting Tuesday, state media said. (AFP)