China's foreign ministry has condemned a denial by the United States that US balloons have unlawfully flown through Chinese airspace, and is seeking a thorough investigation and an explanation.

Chinese foreign ministry spokesperson Wang Wenbin reiterated China's claim about such balloons at a media conference on Tuesday. He argued that the US released more than 10 high-altitude balloons that flew over China and other countries since May last year.

Wang also sought a full investigation by the United States and an explanation to China.

US National Security Council Coordinator for Strategic Communications John Kirby told reporters on Monday that the United States is not flying surveillance balloons over China.