US television network ABC has aired images of a suspected Chinese surveillance balloon that has been observed flying over the continental United States. They show what appears to be black equipment underneath the white balloon.

ABC News quoted a senior government official as saying the balloon is the size of three buses and complete with a technology bay.

The network also reported that a defense official said similar balloon activity has been observed a handful of other times over the past few years, and that "it is appearing to hang out for a longer period of time this time around."

The balloon was spotted above the western state of Montana on Wednesday. The state is located along the border with Canada, and the Rocky Mountains run through part of it. It is also home to an air force base that operates intercontinental ballistic missiles capable of carrying nuclear warheads.