The summer surge in tourists may have contributed to the current COVID-19 outbreak in the Xinjiang Uygur autonomous region, and increased the risk of its spread inside and outside the region, a local health official said.

By the end of Monday, there had been 420 asymptomatic cases since the first case in the latest outbreak was reported in the Ili Kazak autonomous prefecture on July 30. Of them, 338 are located in Ili's Yining city, according to Xinjiang's regional health commission. No confirmed cases have yet been reported.

The virus responsible for the latest outbreak belongs to the Omicron subvariant BA.5.2 which initially arrived from overseas, Cui Yan, deputy director of the commission told a news conference on Monday night.

"The epidemic prevention and control situation in Xinjiang is complex and grim as the region is in its peak tourist season," Cui said. "The flow of people and cross-regional movement may have contributed to the transmission of the virus, and increased the risk of its spread inside and outside Xinjiang."

The outbreak has already hit 10 prefectures and prefecture-level cities in the region, the commission said.

Xinjiang has become one of the country's top tourist destinations this summer. Between July 30 and Aug 7, it received 8.82 million visits. Measures will be taken to protect tourists affected by the outbreak, Yan Naimin, deputy director of Xinjiang's regional culture and tourism bureau, said on Monday.

"Currently, tourism in Xinjiang is both stable and controllable. Special service teams have been set up to ensure a speedy response to tourist demands. Additionally, those who cancel hotel reservations or ticket bookings as a result of the epidemic will receive full and unconditional refunds," Yan said.

The deputy director added that local governments are working to help tourists leave the region in an orderly manner, and have provided them with water, food and other basic necessities. Hotels in areas affected by the outbreak are being encouraged to lower their rates to cater to those unable to leave.

Zheng Mingquan, an official from the transport department of Xinjiang, said on Monday that railways, highways and airports are operating normally in low-risk areas, ensuring the smooth flow of tourists and goods. None of Xinjiang's airports have been closed because of the epidemic. Meanwhile, daily railway services between Yining, the city worst hit by the outbreak, and the regional capital of Urumqi, have been cut from 14 to two.