Mainland China has reported 32 new coronavirus cases as of the end of June 18, 25 of which were reported in the capital city Beijing, China's National Health Commission says.
This compared with 28 confirmed cases a day earlier, 21 of which were in Beijing.
Local authorities are restricting movement of people in the capital and stepping up other measures to prevent the virus spreading further after a series of local infections.
Another five asymptomatic COVID-19 patients, those who are infected with coronavirus but show no symptoms, were also reported as of June 18 compared with eight a day earlier.
China does not count these patients as confirmed cases.
Meanwhile, China has released genome sequencing data for the coronavirus responsible for a recent outbreak in Beijing, with officials saying on Friday it had identified a European strain based on preliminary studies.
China, which had been under pressure to make the data public sooner rather than later as COVID-19 cases mounted in the capital, said it had also submitted the data to the World Health Organization.
Details published on China's National Microbiology Data Center website revealed the genome data was based on three samples - two human and one environmental - collected on June 11.
That was the same day Beijing reported its first new local COVID-19 infection in months. In the eight days since, the city has reported a total of 183 cases, linked to the sprawling wholesale food centre of Xinfadi in the city's southwest.
"According to preliminary genomic and epidemiological study results, the virus is from Europe, but it is different from the virus currently spreading in Europe," Chinese Center for Disease Control and Prevention (CDC) official Zhang Yong said in an article published on Friday. "It's older than the virus currently spreading in Europe."
Zhang said there were several possibilities as to how the virus arrived in China.
"It could have been hidden in imported frozen food products, or it was lurking in some dark and humid environment such as Xinfadi, with the environment not having been disinfected or sterilised," Zhang wrote in the article.
Wu Zunyou, the CDC's chief epidemiology expert, had told state media earlier this week the Beijing strain was similar to Europe's, although not necessarily directly transmitted from European countries. Wu did not elaborate on those comments made before the release of the genome sequence.
Coronavirus strains found in the United States and Russia were mostly from Europe, he added.