Four people tested positive for COVID-19 during a regular nucleic acid tests in Burang county in Ngari prefecture of the Tibet autonomous region on Sunday, according to a statement issued by the prefecture's health authorities on Sunday.

The four cases, all diagnosed as asymptomatic carriers, were detected among tourists from outside the county, the statement said.

Of them, three are from the Samdrubtse district of the region's Shigatse city and one is from Dingri county of Shigatse.

The patients have been sent to designated hospital for treatment, while the close contacts and secondary close contacts have been traced and put under quarantine to curb the spread of virus.

Seven areas in the Burang county have been designated as medium-risk areas for COVID-19.

Tibet had reported no new confirmed or suspected COVID-19 cases for 920 days before the cases emerged on Sunday.