Shanghai authorities doubled down on their offensive against Covid-19 today, launching a new round of city-wide testing and warning residents their three-week lockdown would only be lifted in batches once transmission is stamped out, Reuters reports.

The Shanghai government said on its official WeChat account, the city's epidemic was showing a “positive trend” and that life in the city could return to normal soon as long as people stuck to strict rules to curb the spread of Covid-19.

And while some Shanghai districts tightened restrictions on movement, officials in neighbourhoods that met criteria for people to be allowed to leave their homes were still preventing them from doing so, fuelling anger and frustration among residents who have endured weeks of lockdown.