Beijing on Friday said a "civilian airship" had unintentionally entered American airspace, after the Pentagon earlier announced it was monitoring what it called a surveillance balloon over the US.

In a statement released by the Foreign Ministry late on Friday, officials described the object as a "civilian airship used for research, mainly meteorological, purposes".

"Affected by the westerlies and with limited self-steering capability, the airship deviated far from its planned course," the ministry added.

"The Chinese side regrets the unintended entry of the airship into US airspace due to force majeure."

The statement went on to say that mainland officials will continue communicating with the US side and properly handle the "unexpected situation".

The Pentagon earlier said it had been tracking a suspected "high-altitude surveillance balloon" over the continental United States.

It had recently been spotted over the state of Montana.

In response to that announcement, Foreign Ministry spokesperson, Mao Ning, had said Beijing was working to verify the facts around that claim, and warned against "hype" over the issue.