Chinese-born Guo, who now lives in New York, has emerged in recent months as a political threat to the Chinese government in an acutely sensitive year, making clear that he wants to disrupt a five-yearly congress to be held this autumn.

A sprawling aviation-to-financial services group, HNA has become China's most active non-government enterprise in global markets, with deals worth more than $50 billion.

HNA rebutted Guo's claims on its website, ranging from allegations of shareholdings by senior Chinese government officials and their relatives, to irregularities in global acquisitions, and improprieties over its VIP jet.

"HNA Group reserves right to pursue all legal actions in due course," it added in its website statement late on Saturday.

Through Twitter posts and video blogs, Guo has unleashed a deluge of corruption allegations against high-level Communist Party officials. He began making specific allegations against HNA in April, but the group had not previously replied publicly.

Within hours of HNA's statement, Guo said in a livestreamed video that he welcomed its response, and urged the company to make good on its threat to sue.

"If it's just me speaking, that's no good," he said in the video. "Only their replies can prove the value and the truth of the matter. This is critical."

Guo did not immediately respond to a request for comment from Reuters.

Guo has provided scant evidence to back up his accusations, but his standing as a former billionaire insider, and his close ties with a disgraced former senior intelligence official, have made him a center of attention in Beijing political circles.

The government has launched a sustained effort to discredit Guo, making a request to Interpol in April for the issue of a global 'red notice' for his arrest.

On Friday, three senior employees of Guo told a court he had instructed them to fraudulently obtain loans running into hundreds of millions of dollars.

The chairman of property developer SOHO China, Pan Shiyi, and a prominent journalist, Hu Shuli, the founder of Caixin Media, have also filed defamation suits against Guo in New York.