A growing COVID-19 cluster in China's Dalian has spurred the northeastern port city to limit outbound travel, cut offline school classes and close a few cultural venues after being told by national authorities to contain the outbreak more quickly.

Dalian reported 52 locally transmitted infections with confirmed symptoms on Thursday, a daily count higher than any other Chinese city affected in an ongoing nationwide outbreak since mid-October, and more than doubling from 21 cases a day earlier, official data showed on Friday.

A total of 1,149 local cases were found in China between Oct. 17 and Nov 11. While the number is tiny compared with many outbreaks outside the country, local authorities have exerted resources to put out the flare-up with Beijing not expected to change its zero-tolerance policy any time soon.

"Various measures should be quickened and their quality should be improved, in order to get the outbreak under control in a shorter amount of time and to minimise the outbreak's impact on manufacturing and life of the general public," the National Health Commission said on Thursday, citing a meeting chaired by the commission's director in Dalian.

The number of people travelling out of Dalian has dropped by 96.5% to 918 per day on average, a local transportation official said late on Thursday, after the city of 7.5 million people imposed curbs on public transport and warned residents against leaving Dalian for unnecessary reasons.

The city has demanded kindergartens and primary and high schools halt offline lessons, closed a number of libraries and museums, and started a second round of city-wide mass testing campaign.

On Friday, Dalian called on its residents not to leave their home unless it is necessary.

Dalian, a leading port for seafood shipments as well as fruit and some meats, has also ordered all businesses handling imported chilled and frozen foods to suspend operations, according to the state-backed newspaper Global Times. 

As of Nov. 11, mainland China had reported 98,099 confirmed symptomatic COVID-19 patients, including both local cases and those arriving from abroad. The total death number remained at 4,636.