EFFORTS TO RECOVER remnants of the large balloon shot down off the coast of South Carolina have ended and analysis of the debris reinforces conclusions that it was used for spying by the Chinese, US officials said.

Officials said it is believed that Navy, Coast Guard and FBI personnel collected all of the balloon debris from the ocean floor.

US Northern Command said in a statement that the recovery operations ended on Thursday and that final pieces are on their way to the FBI lab in Virginia for analysis.

It said air and maritime restrictions off South Carolina have been lifted.

The announcement capped three dramatic weeks that saw US fighter jets shoot down four airborne objects — the large China balloon and three much smaller objects over Canada, Alaska and Lake Huron — the first known peacetime shootings of unauthorised objects in US airspace.

The officials also said the search for the small airborne object that was shot down over Lake Huron has stopped and nothing has been recovered.

The US and Canada have also failed to recover any debris from the other two objects which were shot down over the Yukon and northern Alaska.

While the military is confident the balloon shot down off South Carolina was a surveillance airship operated by China, the Biden administration has admitted that the three smaller objects were likely civilian-owned balloons that were targeted during the heightened response, after US homeland defence radars were recalibrated to detect slower moving airborne items.

Due to their small size and the remote areas where they were shot down, officials acknowledge that recovering any debris is difficult and probably unlikely. Those last two searches, however, have not been formally called off.

Much of the Chinese balloon fell into about 50ft (15m) of water, and the Navy was able to collect remnants floating on the surface. Divers and unmanned naval vessels pulled up the rest from the bottom of the ocean.

Northern Command said on Friday that all of the Navy and Coast Guard ships have left the area.