NHC Minister Ma Xiaowei made the comments at a government meeting, where he also said the virus was spreading to rural areas and that the handling of the recent situation had exposed how prevention and control measures had been relaxed.
"Since Dec. 2020, epidemic clusters have occurred in Beijing, Sichuan, Liaoning, Hebei and Heilongjiang," a statement posted on the NHC's website said citing the briefing by Ma.
"They mainly have the following characteristics. Firstly, they are all imported from abroad, caused by travelers from overseas, or contaminated cold-chain imported items."
Total case numbers remain well below what China saw at the height of the outbreak in early 2020, but concerns about a new wave are growing with the Lunar New Year a month away.
This surge comes as a World Health Organization-led (WHO) team of investigators are in quarantine in the city of Wuhan, where the disease was first detected in late 2019. The team aims to investigate the origins of the pandemic that has now killed nearly 2 million people worldwide.
China is the only country to claim COVID-19 can be transmitted via cold chain imports, even though the WHO has downplayed the risks, and has been pushing a narrative via state media that the virus existed abroad before it was discovered late last year in the central city of Wuhan.
The country has in the past week seen the number of daily cases jump to an over 10-month high, and for Jan. 15 reported 130 new coronavirus cases in the mainland, versus 144 cases a day earlier.
Of those cases, 115 were local infections, 90 of which were in Hebei province surrounding Beijing that has been hit hardest in the latest wave.