WASHINGTON – Chinese surveillance balloons flew over the continental United States at least three times during the Trump years, according to a senior administration official, but key details about the incursions were not widely known until after Mr Joe Biden took office.

Former president Donald Trump and some senior officials who worked for him have denied knowing that Chinese airships entered US airspace on their watch.

While some members of the Trump administration eventually realised that the unidentified objects were Chinese spy vessels, those intelligence conclusions often took weeks – particularly because the balloons included jamming systems to hide their true intent, Trump-era officials said.

The former president was never presented an opportunity to shoot balloons down.

Intelligence officials from the Biden administration are willing to provide former Trump national security officials with a briefing about the Chinese surveillance efforts, according to the current administration official, who discussed intelligence matters on the condition of anonymity.

In an interview Sunday with Fox News, Mr Trump accused his successor of claiming Chinese overflights took place during his tenure because “they look so bad”.

“This never happened,” he said. “It would have never happened.”

The three incidents – and a fourth earlier in the Biden administration – were described by the administration official as brief, unlike the overflight last week that saw a balloon fly a lengthy path, cross-cutting the mainland US from Idaho to South Carolina before ultimately being shot down over the Atlantic Ocean.

Mr Trump and other senior Republicans have criticised the Biden administration’s decision to wait until the balloon was over the ocean to shoot it down, more than four days after it was spotted for the second time entering US airspace.

Mr Biden said he instructed the military to shoot the balloon down on Wednesday, but added that the Pentagon recommended they wait to better observe the balloon’s intelligence capabilities and eliminate the risk that falling debris could harm individuals or property on the ground.

The US is currently working to recover debris from the waters off the Atlantic coast, though administration officials say they are confident it was a spy balloon.

China claimed that the balloon was a civilian craft doing weather research that was accidentally blown off course. BLOOMBERG