The United States President Joe Biden called Chinese President Xi Jinping a "dictator" less than one day after US Secretary of State Antony Blinken ended his trip to Beijing to revive better relations.

Blinken's trip comes in light of heightened tensions between the two global powers. The purpose of this visit was to improve relations that had fallen to all-time lows amid US provocations with regard to Taiwan and the South China Sea.

During a speech at a Democratic Party fundraiser in California, Biden claimed that Xi was "upset" because he was not aware that the [Chinese] balloon changed its course and flew over the US before being shot down by the Air Force.

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"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 is he didn't know it was there," Biden said.

"I'm serious. That was the great embarrassment for dictators, when they didn't know what happened," he added.

"That wasn't supposed to be going where it was... and he [Xi] didn't know about it," Biden continued. "When it got shot down he was very embarrassed and he denied it was even there."

Responding to Biden's comments Wednesday, Beijing slammed them as an "open political provocation."

"The relevant remarks by the US side are extremely absurd and irresponsible, they seriously violate basic facts, diplomatic protocol and China's political dignity," Foreign Ministry spokeswoman Mao Ning told a briefing.

"China is strongly dissatisfied with and firmly opposed to this," she added.

Commenting on Blinken's recent visit to China, the US President considered that "we're in a situation now where he wants to have a relationship again."

The US Secretary of State "did a good job" on his China trip, but "it's going to take time," Biden added.

Blinken's visit was originally planned to take place in February but was postponed following heightened tensions between the two countries after Washington claimed that a Chinese "spy" balloon flew over the country's airspace.

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On Monday, Biden said the relationship between the US and China is on the "right trail" following Blinken's visit to Beijing during which he met and spoke with top Chinese leaders, including Xi. 

Blinken reiterated several times throughout his visit that the US does not support Taiwan's independence, but China's "proactive actions" were cause for concern in the region. 

Touching upon the recent summit held by Quad leaders, consisting of the US, Australia, India, and Japan, the US President confirmed that the security bloc is "working hand in glove in the South China Sea and the Indian Ocean."

"What he (Xi) was really upset about was that I insisted that we unite the... so-called Quad," Biden said.

The anti-China coalition, which was established in 2004, was dismantled in 2008 over Australian fears of upsetting Beijing and American declined interest. The assembly was later revived in 2017 during the former US President Donald Trump's administration as the American leader adopted a hostile foreign policy on China.