China's capital Beijing tightened Covid restrictions on as it battled an outbreak, while Shanghai let some of its 25 million residents venture out for light and air after reporting a second day of zero infections outside of quarantine areas.

Shanghai's outbreak, which began in March, has been China's worst since the early months of the pandemic in 2020. Hundreds of thousands have been infected and the city has forbidden residents from leaving their homes, to great public anger, Reuters reports.

The outbreak in China's most populous city and the risk of a spread in Beijing are testing the government's zero-Covid approach in a year when Xi Jinping is expected to secure an unprecedented third term as president.