A passenger from Singapore to Putian, Fujian province suspected of triggering a local COVID-19 outbreak likely contracted the novel coronavirus while in centralized quarantine in the province, a public health expert said on Thursday.

Wang Huaqing, a chief expert from the Chinese Center for Disease Control and Prevention, said the tentative finding is based on epidemiological investigation, as well as the results of genome sequencing and antibody testing.

The male passenger returning from Singapore in early August had reportedly tested negative for the novel coronavirus nine times during a period of 21 days in centralized isolation.

He tested positive for the virus on Sept 10 after his two children were found to be infected.