URUMQI -- Northwest China's Xinjiang Uygur autonomous region has identified 137 new asymptomatic cases of COVID-19, as of 2 pm on Sunday, a local health official said at a press conference.

All the new cases were reported in south Xinjiang's Kashgar prefecture after a 17-year-old female villager from the prefecture's Shufu county was confirmed as an asymptomatic carrier of the virus on Saturday during routine nucleic acid testing.

The cases were all found related to a factory in Shufu where the parents of the female villager work, Gu Yingsu, deputy director of the regional health commission, said at the press conference.

She has been placed under quarantine for medical observation at a designated hospital in Kashgar, and has yet developed symptoms such as fever or cough, according to the health commission.

An epidemiological investigation that started on Saturday has combed all the close contacts of the new cases and those at risks, and health quarantine measures have been in place among them, Gu added.

Kashgar has taken samples from over 2.83 million residents since Saturday, with test results obtained for 334,800 people. The prefecture vowed to provide tests to about 4.75 million people in total including 245,000 in Shufu.