China said Thursday that it will allow foreign air carriers to increase their flights to the country next week, depending on the number of passengers infected with the new pneumonia-causing coronavirus.

Since March, foreign airlines have been limited to operating their flights to China from abroad only once a week. Beijing said it will give the green light for them to fly more frequently from next Monday, provided they have no passenger who tests positive for the virus.

People wait at a boarding area for domestic flights at Beijing Capital International Airport on May 10, 2020. (Kyodo)

Foreign carriers can fly into China twice a week on the same route if infection cases are not confirmed among their passengers on one flight for three weeks.

Conversely, if five or more passengers test positive for the virus, the carrier must suspend its flights to China for one week. If the number reaches 10 or above, they will be barred from services to China for four weeks.

The announcement came shortly after Washington said Wednesday that it will block Chinese passenger airlines from flying into and from the United States starting June 16, in response to what it views as China's unfair treatment of U.S. carriers during the pandemic.

The United States has claimed that a notice issued by Beijing on March 26 has effectively precluded U.S. carriers from restarting passenger flights to and from China, intensifying already strained ties between the world's two major powers.

By mid-March, three U.S. carriers -- American Airlines Inc., Delta Airlines Inc. and United Airlines Inc. -- had completely ceased passenger flights to and from China.

Under the new rule, U.S. air carriers are expected to be permitted to fly into China, foreign affairs experts say.

China has "maintained close communication on flight arrangements" with the United States, Foreign Ministry spokesman Zhao Lijian told reporters on Thursday.

"The two sides have already made some progress, and China has also announced relevant policy adjustments. We hope that the United States will not create obstacles for both to solve the problem," Zhao said.