In the latest jab over aerial surveillance, China said on Monday that high-altitude balloons from the United States had flown over Chinese airspace without permission more than 10 times since the start of last year.

China’s claims could not be immediately corroborated. But Wang Wenbin, a foreign ministry spokesman, said that it was a “common occurrence” for U.S. high-altitude balloons to “illegally enter the airspace of other countries,” while providing no further details.

He also reiterated Beijing’s position that the Chinese balloon that floated over the United States this month before being shot down was a civilian airship that had accidentally strayed into American airspace. U.S. officials called it a surveillance craft.

Mr. Wang urged the United States “to reflect on itself and mend its ways, instead of slandering, smearing or inciting confrontation.”

The comments, made at a news briefing by China’s Ministry of Foreign Affairs, followed a busy weekend of aerial theatrics as U.S. fighter jets shot down three unidentified flying objects over North America. American officials are still uncertain about what the objects were, who sent them and what purpose they were meant to serve.

In China, the local authorities near a northern port city said on Sunday that they had spotted their own unidentified flying object and were prepared to shoot it down, according to Chinese state-owned media.

A local government marine agency warned nearby fishing boats to be careful of possible falling debris, the report said. But as of Monday afternoon in Beijing, there was no official announcement about the object or whether authorities had fired at it.

President Biden ordered the U.S. military to shoot down the Chinese balloon off the coast of South Carolina on Feb. 4, a few days after it was spotted hovering over Montana.

The balloon’s discovery prompted Secretary of State Antony J. Blinken to cancel a planned visit to Beijing over what he called an “irresponsible act.” A senior administration official said the craft had flown over sensitive military sites in the United States and Canada.