Beijing raised a residential community to medium-risk level amid COVID-19 control and prevention efforts on Friday as a recent coronavirus outbreak related to a tour group has spread to 10 provinces and autonomous regions, as well as the capital, as of Friday.

The country has reported more than 70 locally transmitted cases during this round of the outbreak as of Friday, with cases involving those who either have traveled to north and northwestern China or have had close contact with those who were recently in the region.

Beijing reported four locally transmitted cases in a residential community in Changping district on Friday and afterward the local authority raised the COVID-19 risk level to medium.

The four confirmed cases, including a couple, had traveled to the Inner Mongolia autonomous region and the Ningxia Hui autonomous region, as well as Shaanxi province between Oct 12 and Oct 15 by car.

Pang Xinghuo, deputy director of the Beijing Center for Disease Control and Prevention, said at a news conference on Thursday that the new infections belong to the same transmission chain as recent cases in other provinces.

As more details of the new cases are known, an increasing number of cases are believed to be linked to a restaurant in Ejin Banner, Alxa League, Inner Mongolia.

Up to nine new local cases were reported in Ejin as of 1:16 pm on Friday, which has led to a total of 23 confirmed cases in Ejin, in western Inner Mongolia, 1,000 kilometers from Hohhot, the regional capital.

On Oct 12, a tour group of seven seniors dined in the restaurant and were all later confirmed as infected patients. On the same day, another tour group of five from Gansu province dined in the restaurant and all of them were also infected.

Previously, five restaurant employees were confirmed as COVID-19 cases.

The restaurant is 81 km from Ceke Port, the third-largest land port in Inner Mongolia, bordering Mongolia.

Port officials have examined 70,000 individuals, 70,000 vehicles and 3.66 million metric tons of goods since the beginning of the year.

Local news outlets reported the potential risk of imported infections at the land port.

Chang Rongshan, a virology expert at Shantou University, told a local newspaper that it's highly possible that the tour group was infected at the restaurant.

"Tracing back several transmission chains, it was found that the cluster began in that restaurant,"Chang said.

As winter arrives, it will be a major task for Ceke Port to accelerate Customs clearance of coal loaded via vehicles from Mongolia into China. The port has been asking drivers to take nucleic acid tests the day of entry, which might have led to the virus being in the area due to the pathogen's incubation period, he said.

"In addition, the fact that the area is sparsely populated means it is likely that the virus has been around the place for a certain period," he added.