China lashed back Wednesday over U.S. President Joe Biden referring to President Xi Jinping as a "dictator" at a donor conference.

Beijing said the remarks were absurd and a provocation, in an unexpected spat immediately following efforts by both sides to lower tensions.

Biden's comments came just a day after top U.S. Secretary of State Antony Blinken visited Beijing to stabilize bilateral relations that China says are at their lowest point since formal ties were established.

Attending a fundraiser in California, Biden said Xi was very embarrassed when a suspected Chinese spy balloon was blown off course over U.S. airspace early this year, making a personal comment on the Chinese leader when Blinken said Monday the "chapter" should be closed.

"The reason why Xi Jinping got very upset in terms of when I shot that balloon down with two box cars full of spy equipment in it was he didn't know it was there," Biden said.

"That's a great embarrassment for dictators. When they didn't know what happened. That wasn't supposed to be going where it was. It was blown off course," Biden added.

Xi became China's most powerful leader since Mao Zedong after securing a precedent-breaking third term as president in March and head of the Communist Party in October.

Biden also said China "has real economic difficulties."

A Chinese foreign ministry spokesperson said Biden's remarks were "extremely absurd" and "irresponsible."

Foreign ministry spokesperson Mao Ning expressed China's strong dissatisfaction and said Biden's comments seriously violated facts, diplomatic protocol and China's political dignity.

"They're an open political provocation," she told a news conference.

It was unclear why Biden said Xi was unaware of the whereabouts of the balloon and when asked whether Xi knew its location, Mao reiterated China's previous explanation that the passage of the balloon through U.S. airspace had been unintended and caused by circumstances beyond its control.

No breakthroughs

Biden's comments came after Blinken and Xi agreed in their meeting Monday to stabilize the intense rivalry between Washington and Beijing so it did not veer into conflict.

While no breakthroughs were made during the first visit to China by a U.S. secretary of state for five years, both sides did agree to continue diplomatic engagement with more visits by U.S. officials in the coming weeks and months.

Biden said later Tuesday that U.S. climate envoy John Kerry may go to China soon.

A day earlier, on Monday, Biden said he thought relations between the two countries were on the right path and he indicated that progress was made during Blinken's trip.

Biden said Tuesday that Xi had been concerned by the so-called Quad strategic security group, which includes Japan, Australia, India and the United States.

The U.S. president said he had previously assured Xi that the United States was not trying to encircle China with the Quad.

"He called me and told me not to do that because it was putting him in a bind," Biden said.

Later this week, Biden will meet Indian Prime Minister Narendra Modi and China is expected to be a topic of discussion between the two leaders.