The novel coronavirus is spreading in multiple regions on the Chinese mainland, with the coastal province of Guangdong facing a complicated situation, the National Health Commission said over the weekend.

The Chinese mainland registered 112 locally transmitted confirmed infections on Saturday, up from 93 on Friday, the commission said.

Mi Feng, a spokesman for the commission, said during a news briefing on Saturday that 15 provincial-level regions had reported domestic cases in the past week, underscoring the need to roll out rapid and aggressive virus control measures.

The domestic infections reported on Saturday include 26 in Shenzhen and 22 in Dongguan, two densely populated cities in Guangdong in South China.

Wu Liangyou, deputy director of the commission's Bureau of Disease Prevention and Control, said the transmission chain in Shenzhen is complex and the risk of it spreading further is high.

The city has detected several infection clusters in different districts since Feb 15. Genome sequencing results pointed to the infections being the highly transmissible Omicron variant, according to the local government.

In Dongguan, most infections were concentrated in a local industrial park.

Zhai Xianchun, an official with the Dongguan municipal government, said at a news conference on Saturday that the city, a major manufacturing hub, is seeing a travel rush of workers as factories resume production following Spring Festival.

"It is challenging to track down people at risk and manage their movement," he said, adding that the Dongguan outbreak was triggered by the Omicron variant.

Wu, from the commission, said screening and tracking high-risk groups is underway to curb the spread of the virus in Dongguan.

The Inner Mongolia autonomous region reported 38 cases on Saturday, but the risk of the virus further spreading has been reduced, he said.

However, infection clusters in some border regions in the Guangxi Zhuang autonomous region, as well as Yunnan and Heilongjiang provinces, are still developing.

Wu said China's virus control approaches are effective against the Omicron variant－the dominant strain globally－and the key to containing its spread is to fully implement the correct control measures.

According to the commission, China has fully vaccinated over 1.23 billion people as of Friday. Nearly 555 million people have received a booster shot.