WASHINGTON, United States - The United States has completed the search for debris from an alleged Chinese surveillance balloon it shot down earlier this month, the military's Northern Command said Friday.

"Recovery operations concluded February 16 off the coast of South Carolina, after US Navy assets assigned to US Northern Command successfully located and retrieved debris from the high-altitude PRC surveillance balloon," NORTHCOM said in a statement, referring to the People's Republic of China.

"Final pieces of debris are being transferred to the Federal Bureau of Investigation Laboratory in Virginia for counterintelligence exploitation," it added.

The balloon traveled across much of the United States before it was shot down over the Atlantic Ocean by a US F-22 Raptor on February 4.

Beijing insisted the device was for weather surveillance and had gone astray, while Washington described it as a sophisticated high-altitude spying vehicle.

Relations between China and the United States have grown increasingly tense over the balloon incident.

US jets also shot down three unidentified objects in subsequent days, but Washington has said preliminary evidence suggests those objects were not involved in a broader Chinese spy program.