US President Joe Biden says he expects to speak with China’s President Xi Jinping about a suspected Chinese spy balloon shot down over the US.

“We are not looking for a new cold war,” President Biden said on Friday (Australian time).

In his most extensive remarks yet about the Chinese balloon shot down on February 4 and three other unidentified objects downed by US fighters, Mr Biden did not say when he would speak with Mr Xi.

He also said the US was continuing to engage diplomatically with China on the issue.

“I expect to be speaking with President Xi, I hope we are going to get to the bottom of this, but I make no apologies for taking down that balloon,” he said in response to complaints from Beijing.

After the speech, Mr Biden told NBC News: “I think the last thing that Xi wants is to fundamentally rip the relationship with the United States and with me.”

China says the 60 metre balloon was for monitoring weather conditions, but Washington says it clearly was a surveillance balloon with a massive undercarriage containing electronics.

Mr Biden, who had made few public comments about the spate of aerial objects that began with the spotting of the Chinese balloon, broke his silence after lawmakers demanded more information on the incidents, which have baffled many Americans.

He said the US intelligence community was still trying to learn more about the three unidentified objects: One that was shot down over Alaska, one over Canada and a third that plunged into Lake Huron. The administration has said they were downed because they posed a threat to civil aviation.

“We don’t yet know exactly what these three objects were, but nothing right now suggests they were related to the Chinese spy balloon program or they were surveillance vehicles from any other country,” Mr Biden said.

The intelligence community believes the objects were “most likely balloons tied to private companies, recreation or research institutions”, Mr Biden said.

He said they might have been spotted due to radar that was enhanced in response to the Chinese balloon.

“That’s why I’ve directed my team to come back to me with sharper rules for how we will deal with these unidentified objects moving forward, distinguishing between those that are likely to pose safety and security risks that necessitate action and those that do not,” he said.

Mr Biden’s remarks followed reports the Chinese balloon, downed on February 4 after crossing the continental US, originally had a trajectory that would have taken it over Guam and Hawaii but was blown off course by prevailing winds.

Asked in advance about Mr Biden’s remarks, a China foreign ministry spokesman on Thursday once again referred to the downed balloon as an “unmanned civilian airship”, and said its flight into US airspace was an “isolated” incident.

The US “should be willing to meet China in the middle, manage differences and appropriately handle isolated, unexpected incidents to avoid misunderstandings and misjudgments; and promote the return of US-China relations to a healthy and stable development track,” spokesman Wang Wenbin told reporters at a regular briefing.

Beijing had criticised Washington for overreacting by shooting down the balloon, and warned of “countermeasures against relevant US entities that undermine China’s sovereignty and security”.

On Thursday, China put Lockheed Martin and a unit of Raytheon Technologies on an “unreliable entities list” over arms sales to Taiwan, banning them from imports and exports related to China in its latest sanctions against the US companies.

Lockheed makes the F-22 Raptor fighter jet that flew the mission to shoot down the Chinese balloon and Raytheon makes the AIM-9X Sidewinder missile that blew it out of the sky.

– AAP