The Chinese balloon that flew over the US earlier this year managed to gather intelligence from military bases for days before it was shot down, US media report.

The balloon was able to transmit data to Beijing in real time, NBC News reported, citing US officials.

The craft picked up electronic signals rather than taking pictures, according to one official quoted by the network.

The White House didn't confirm the report.

But US officials say they managed to limit the balloon's intelligence-gathering abilities as it floated over the country.

On Monday, a defence department spokesperson said that the FBI was still examining the balloon debris.

"We do know that the balloon was able to be manoeuvred and purposely driven along its track," said spokesperson Sabrina Singh, who declined to say which military installations the balloon was able to hover over.

"We're still doing an assessment of what the intel was that China was able to gather but we do know that the steps that we took provided little additive value to what they've been able to collect on from satellites before," she said.

US officials say they tracked the balloon over Alaska and Canada before it re-entered American airspace in early February.

A public acknowledgement that the balloon was flying over the continental US set off days of tracking, sky watching and speculation. The craft - which was about 200ft (60m) tall - was shot down off the coast of South Carolina on 4 February by a US fighter jet.

American officials later said they had recovered the balloon. Chinese officials say it was a civilian weather balloon and that the US overreacted by shooting it down.

Officials told US media that China was able to control the balloon so it could make multiple passes over military bases, sometimes flying in a figure-eight loop.

The incident triggered a diplomatic row and led US Secretary of State Antony Blinken to cancel a trip to China.

In the weeks after the balloon was shot down, US fighter jets shot down several other balloons they suspected had originated in China. The US defence department says China operates a fleet of balloons around the world.