Millions of people in Shanghai queued for a third day of mass COVID-19 testing on Thursday as authorities in several Chinese cities scrambled to stamp out new outbreaks that have rekindled worries about growth in the world's second-largest economy, News.az reports citing Xinhua.

Unless local officials succeed in preventing the virus from spreading, they could be compelled to invoke prolonged, major restrictions on residents' movement, under China's "dynamic zero COVID" strategy.

Having just emerged from a painful two-month lockdown, Shanghai was again on high alert as it raced to isolate infections linked to karaoke services that had been taking place illegally.

Urging karaoke joints to abide by COVID rules and make sure customers had undergone tests, Shanghai resident Qiu Shijia had a message for their owners: "Don't push your luck."

Qiu was among a number residents Reuters spoke with in China's most populous city that were wary of a return to restrictions that had caused mental stress, and financial hardship for many people, and disrupted global supply chains and overseas trade.