China said on Monday (Feb 13) that US high-altitude balloons had flown over its airspace without permission more than 10 times since the beginning of 2022, drawing a swift denial from Washington.

China's accusation widened a diplomatic row after the US military shot down what it says was a Chinese spy balloon.

"Since last year, the US' high-altitude balloons have undergone more than 10 illegal flights into Chinese airspace without the approval of the relevant Chinese departments," Chinese foreign ministry spokesperson Wang Wenbin said at a regular briefing in Beijing in response to a question.

Wang did not specifically describe the balloons as flying for military or espionage purposes and did not provide further details.

Asked how China had responded to such incursions into its airspace, Wang said its responses had been "responsible and professional".

The White House promptly denied China's accusation, which National Security Council spokeswoman Adrienne Watson dismissed as an effort at damage control by Beijing. "Any claim that the US government operates surveillance balloons over the PRC (People's Republic of China) is false," she said in a statement.

"It is China that has a high altitude surveillance balloon program for intelligence collection, connected to the People’s Liberation Army, that it has used to violate the sovereignty of the United States and over 40 countries across five continents," she said.

China has failed to offer "any credible explanations" for the intrusions, she added.

Earlier, national security spokesman John Kirby said in a television interview: "Just absolutely not true. We are not flying balloons over China."

The US Defense Department did not immediately respond to a request for comment.

China's assertion comes after the US shot down what it says was a Chinese spy balloon off the coast of South Carolina on Feb 4 after it had drifted across the continental United States for days.

China says the balloon was a civilian research craft that had mistakenly blown off course and accused the United States of overreacting.

"The first thing the US side should do is to look at itself, to change its ways, not to smear and incite confrontation," Wang said.