The North American Aerospace Defense Command (NORAD) said in a statement it had detected the balloon traveling at an altitude between 43,000-45,000 feet (13,100-13,700 meters), CBS News reported.

"The balloon was intercepted by NORAD fighters over Utah, who determined it was not maneuverable and did not present a threat to national security," the joint agency said.

The US Federal Aviation Administration (FAA) "also determined the balloon posed no hazard to flight safety," according to NORAD.

"NORAD will continue to track and monitor the balloon," it added.

An unnamed US official told CBS News the balloon had a cube-shaped box about two feet long on each side hanging below it.

In February last year, the United States shot down a huge white balloon from China after it was spotted over a series of nuclear weapons sites.

Beijing denied it was a spy balloon, saying the craft was used for weather research and had blown off-course.