China threatens 'further actions' after Joe Biden orders US to shoot down 'spying' balloon

​China has threatened "further actions" after the US shot down a suspected spy balloon, with Beijing insisting it was a civilian aircraft and the flyover was an accident.

US president Joe Biden ordered the craft shot down on Saturday after it had crossed over sensitive military sites across North America.

Pentagon officials say an F-22 fighter jet fired a missile at the balloon at 2:40pm EST (7:40pm GMT), puncturing it while it was off the coast near Myrtle Beach, South Carolina. The Navy is taking the lead in an operation to recover the remnants.

"They successfully took it down and I want to compliment our aviators who did it," Mr Biden said after getting off Air Force One en route to Camp David.

A large balloon drifts above the Atlantic Ocean, just off the coast of South Carolina, with a fighter jet and its contrail seen below it. Picture: Chad Fish via AP

China responded saying it reserved the right to "take further actions" and criticised the US for "an obvious overreaction and a serious violation of international practice".

In its statement on Sunday, China's Ministry of Foreign Affairs said "China will resolutely uphold the relevant company's legitimate rights and interests, and at the same time reserving the right to take further actions in response".

The presence of the balloon in the skies above the US this week dealt a severe blow to already strained US-Chinese relations that have been in a downward spiral for years.

It prompted Secretary of State Antony Blinken to abruptly cancel a high-stakes Beijing trip aimed at easing tensions.

The spectacle had Americans looking to the skies all week, wondering whether the mysterious balloon had floated over them.

US defence and military officials said on Saturday the balloon entered the US air defence zone north of the Aleutian Islands on January 28 and moved largely over land across Alaska and then into Canadian airspace in the Northwest Territories on Monday.

It crossed back into US territory over northern Idaho on Tuesday – the day the White House said Mr Biden was first briefed on it.

The balloon was spotted on Wednesday over Montana, which is home to one of America's three nuclear missile silo fields at Malmstrom Air Force Base.

The Americans were able to collect intelligence on the balloon as it flew over the US, giving them a number of days to analyse it and learn how it moved and what it was capable of surveying, a senior defence official said. The official was not authorised to discuss the ongoing operation and spoke on condition of anonymity.

China has continued to claim the balloon was merely a weather research "airship" that had been blown off course.

The Pentagon rejected that out of hand – as well as China's contention that it was not being used for surveillance and had only limited navigational ability.