Chinese Foreign Ministry said Thursday China has no intention to interfere in the U.S. election, in response to reports that U.S. President Donald Trump pleaded with Chinese President Xi Jinping for help to win the reelection in 2020.

China has always adhered to the principle of non-interference, stressed spokesperson Zhao Lijian at a regular briefing.

In a key meeting with Xi last June, Trump "stunningly turned the conversation to the U.S. presidential election, alluding to China's economic capability to affect the ongoing campaigns, pleading with Xi to ensure he'd win," U.S. president's former national security advisor John Bolton writes in an explosive new behind-the-scenes book.

A book excerpt was published in the New York Times ahead of its release.

Trump hit back at Bolton, calling him "a liar" in an interview with the Wall Street Journal. In a separate interview, Trump told Fox News that Bolton had broken the law by including highly classified material in the book.

Democratic political opponent Joe Biden said in a statement: "If these accounts are true, it's not only morally repugnant, it's a violation of Donald Trump's sacred duty to the American people."