WASHINGTON, Feb 5 (AFP) - The United States military has shot down a suspected Chinese spy balloon off the coast of South Carolina, a week after it entered US airspace and triggered a dramatic spying saga that worsened relations between Beijing and Washington.

President Joe Biden said on Saturday that he had issued an order on Wednesday to take down the balloon, but the Pentagon had recommended waiting until it could be done over open water to safeguard civilians from debris crashing to Earth.

The balloon had been flying at about 18,300 metres (60,000 ft).

“We successfully took it down, and I want to compliment our aviators who did it,” Biden told reporters.

Multiple fighter and refuelling aircraft were involved in the mission, but just one — an F-22 fighter jet from Langley Air Force Base in Virginia — took the shot at 2:39pm local time (19:39 GMT) using a single AIM-9X supersonic, heat-seeking, air-to-air missile, a senior US military official said.

The shootdown came shortly after the US government ordered a halt to flights around the South Carolina coast due to what it said at the time was an undisclosed “national security effort”.

Television footage showed a small explosion, followed by the balloon descending towards the water. The Associated Press news agency said an operation was under way in US territorial waters in the Atlantic Ocean to recover debris from the balloon.

US Secretary of Defense Lloyd Austin called the operation a “deliberate and lawful action” that came in response to China’s “unacceptable violation of our sovereignty”.

He said the balloon was being used by China “in an attempt to surveil strategic sites in the continental United States”.