Hangzhou, capital city of East China's Zhejiang province, reported 4 new confirmed locally transmitted COVID-19 cases in the first 10 hours on Friday, Sun Liming, deputy director of the Zhejiang Provincial Health Commission, said at a news conference.

The new cases bring the total number to 20 since infected cases were first recorded in the city on March 5.

Of the 20 confirmed cases, 16 were diagnosed in the city's Yuhang district, with all the patients working in a parcel distribution center and believed to have contracted the virus through contaminated international mail. Of the 320 environmental and physical samples collected in mails and packages, 25 tested positive, according to Wang Xuchu, deputy director of the Hangzhou Municipal Health Commission.

On Thursday evening, local residents in Hangzhou who may have handled packages or items connected with the distribution center received a text message from health authorities urging them to take a nuclei acid test.

Since March 3, when new cases were reported in Zhejiang's Wenzhou city, the province has recorded 34 confirmed cases and 1 asymptomatic case — all Omicron variant. Apart from Hangzhou and Wenzhou, Jiaxing, Quzhou and Huzhou also reported infected cases.

Qi Xiao in Hangzhou contributed to the story.