Passengers wear face masks upon their arrival at Beijing Capital Airport, in Beijing on March 4, 2020. [Photo/Agencies]

China's civil aviation regulator will reduce the number of international flights in and out of the country in a bid to curb contagion via air travel and contain the rising number of imported cases of the novel coronavirus.

From March 29, domestic airlines are required to reduce their international routes to only one per country and cap the number of flights to no more than one flight per week, while foreign carriers allowed to maintain only one air route to China and operate no more than one flight a week, according to a notice issued by the Civil Aviation Administration on Thursday night.

"The number of imported cases has maintained double-digit growth in recent days, posing great challenge to the domestic epidemic prevention and control achievements and resumption of work and production, as well as public health safety," the administration said later in another statement.

"But we will maintain the minimum number of flights per route to ensure the continuous operation of international flights," the administration said.

With the measure taken, the number of weekly flights will drop to around 130, it said.

As airlines are required to limit the passenger capacity on international flights at 75 percent to curb the infection risks, the number of inbound air travelers is estimated to drop from the current 25,000 to 5,000 each day, it said.

The administration also noted that that it might put in place even further reductions to inbound and outbound international flights in line with the country prevention and control needs.

Though suspending all inbound charter fights since Tuesday, it will arrange temporary flights or chartered flights to bring back overseas Chinese in cities with mass demands and capability to receive flights, it said.

As the pandemic has been raging beyond the country's borders, and the country is facing a new infection threat from overseas arrivals, it's the second time that the civil aviation authority cut down the international flights.

International flights to Beijing have also been diverted to a dozen cities and provinces including Shanghai, Tianjin and Shandong province, where all passengers must be tested for the virus upon disembarkation, before those cleared of the pathogen allowed to re-board the aircraft to the capital.

As of Wednesday, a total of 40 flights bound for Beijing have been diverted to the designated airports, with nearly 70 percent of the 11,284 passengers failing to pass the health and quarantine inspection and staying in the entry cities for a 14-day isolation, the administration said.

"Based on the current operation of diverting international flights due to arrive in Beijing to other airports as their first port of entry, only less than 30 percent of the passengers meet the entry conditions into Beijing," it said. "As long-distance travel does have certain risks, traveler should make prudent, thorough and calm decisions."