Seven positive cases were detected during a mass nucleic acid testing campaign in Zhuhai, Guangdong province, on Friday and preliminary gene sequencing indicated they were infected by the Omicron variant, Zhang Chen, vice-mayor of Zhuhai, said at a news conference on Friday night.

The southern metropolis immediately launched a citywide nucleic acid testing campaign when a local resident in Tanzhou township tested positive during a routine round of testing on Thursday morning.

To curb the spread of the novel coronavirus, Zhuhai has suspended all cross-city bus services starting Thursday, authorities said.