The number of COVID-19 cases in Heilongjiang and Jilin provinces in Northeast China has soared, with 101 newly confirmed cases on Wednesday, including one related to a cluster of infections in Beijing, provincial health authorities said.

Of the confirmed cases, 68 were found in Heilongjiang, data from National Health Commission showed on Thursday. Among the cases, one in Harbin, Heilongjiang, was the mother of a confirmed case in Beijing's Daxing district.

The 67-year-old woman returned to Harbin on Jan 13 by train from Beijing and was diagnosed as a confirmed case on Wednesday.

"We have traced all 71 passengers to Heilongjiang who were in the same coach," Liu Yancheng, a provincial health commission official, said on Thursday, adding that work on tracing more than 800 passengers and staff members on the train is underway.

Along with the screening process adopted in Heilongjiang surrounding the case, Beijing rolled out more measures to control the cluster of infections in Daxing.

On Wednesday, Beijing reported two newly confirmed local cases and one asymptomatic case－all from Daxing's Ronghui residential community, where 10 confirmed cases have been found since Sunday, Pang Xinghuo, deputy head of the Beijing Center for Disease Control and Prevention, said on Thursday.

On Wednesday, Pang said two of the patients in Daxing were carrying a highly transmissible variant of the novel coronavirus first detected in the United Kingdom.

Han Xinxing, executive deputy head of Daxing district, said it had collected around 1.56 million samples for nucleic acid testing by 2 pm Thursday, basically covering all the residents in Daxing.

Daxing is encouraging companies and related institutions to provide free housing or rent reductions to migrant construction workers who will stay in the district during next month's Spring Festival, and they are also being encouraged to pay bonuses to workers.

Han said the district has prepared 39 hotels with 3,424 rooms for possible use as isolation locations for centralized quarantine.

Meanwhile, 1,900 rooms in hotels in other districts, including Chaoyang, have been prepared in case they are needed.

The cluster of infections in Heilongjiang has spread to more cities and other provinces, including neighboring Jilin.

The cluster in Heilongjiang is mainly in Suihua's Wangkui county, which had 65 of the 68 newly confirmed cases in the province.

Jilin reported 33 newly confirmed cases on Wednesday, taking the confirmed caseload in the province to 162 since asymptomatic carriers returning from Heilongjiang triggered an outbreak.

In Shandong province, Pingdu, a county-level city in Qingdao, reported one newly confirmed case and one asymptomatic carrier on Wednesday, all related to Heilongjiang, according to the provincial health commission.

The two patients－a couple－left Suihua on Jan 11, returned to their home in Pingdu on Jan 14, and tested positive on Wednesday, the commission said.

Improvement has been seen in Hebei province, which saw a third successive day with fewer than 50 newly confirmed cases on Wednesday, the Hebei Provincial Health Commission said.

The province identified 20 newly confirmed cases and four asymptomatic carriers on Wednesday.

Also on Wednesday, the province discharged eight COVID-19 patients and 17 asymptomatic carriers from hospital, increasing total recoveries to 65 since Jan 13, when the first recovered patients were discharged.

In Sanhe, a county-level city in Langfang, Hebei, that neighbors Beijing's Shunyi and Tongzhou districts and is home to many people who commute to Beijing for work, normal transport links with the capital have resumed.

People traveling to Beijing need to be able to show a negative nucleic acid test result from the previous 72 hours if their journeys are necessary, Wang Linhui, vice-mayor of the city, said on Thursday.