U.S. President Joe Biden on Tuesday called Xi Jinping a dictator, a day after top U.S. diplomat Antony Blinken visited Beijing to stabilize bilateral relations that China says are at their lowest point since formal ties were established.

Biden also 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 on Monday the "chapter" should be closed.

It was unclear why Biden made the comments on Xi – China's most powerful leader since Mao Zedong after he secured a precedent-breaking third term as president and head of the Communist Party.

"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 at a fundraiser in California.

"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.

Biden also said China "has real economic difficulties."

Xi, who met with Blinken on Monday, has not publicly responded to Biden's comments but they are unlikely to go down well in Beijing and could jeopardise efforts by both countries to bring their relationship back to a more stable footing after the balloon incident.

Blinken and Xi agreed in their meeting to stabilize the intense rivalry between Washington and Beijing so it did not veer into conflict, but failed to produce any breakthrough during a rare visit to China by the secretary of state.

They did agree to continue diplomatic engagement with more visits by U.S. officials in the coming weeks and months. Biden said later on Tuesday that U.S. climate envoy John Kerry may go to China soon.

Biden said on Monday 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 on 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 previously told Xi the U.S. 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.

(Reuters)

Biden calls Chinese President Xi a dictator