A grand jury investigation into Hunter Biden's taxes is the "least damaging" allegation against President-elect Joe Biden's son, Sen. Tom Cotton, R-Ark., said Thursday, pointing out a "far-reaching" probe into Biden's son's foreign business dealings, including with China. 

"The Biden campaign released details of a tax fraud investigation in Wilmington. I think that was just to show maybe the least damaging part of the investigation. There are allegations of securities fraud, money laundering related to Hunter Biden's Chinese businesses, a crooked hospital deal with Jim Biden, Joe Biden's brother out in western Pennsylvania. These investigations span multiple jurisdictions," Cotton said on "America's Newsroom," calling for a special counsel to be appointed to continue the investigation after Biden takes office.

HUNTER BIDEN 'TAX AFFAIRS' UNDER FEDERAL INVESTIGATION; LINKS TO CHINA FUNDS EMERGE, SOURCES SAY

"If Joe Biden becomes president, then all those prosecutors are in line to be fired next month. If there were ever circumstances that create a conflict of interest and call for a special counsel, that's here."

Hunter Biden on Wednesday acknowledged that he has been under a grand jury investigation through the U.S. Attorney’s Office in Delaware since 2018 over his "tax affairs." Biden's father was not a target of the investigation, a source told Fox News.

Hunter Biden’s past dealings with Chinese nationals – including some flagged for “potential financial criminal activity” – are outlined in a Senate committee report reviewed by Fox News.

It was unclear whether any of the specific transactions detailed in the Senate panel’s report were among those being investigated by the U.S. attorney. But the transactions offer a glimpse into Hunter Biden’s alleged activities prior to the launch of the grand jury investigation in 2018.

HUNTER BIDEN'S FOREIGN TRANSACTIONS REPEATEDLY FLAGGED AS POTENTIAL CRIMINAL ACTIVITY, SENATE PROBE FOUND

The report – prepared by the Senate Homeland Security and Governmental Affairs committee – details the younger Biden’s associations with Ye Jianming, founder of CEFC China Energy Co., and his business associate Gongwen Dong.

“Hunter Biden had business associations with Ye Jianming, Gongwen Dong and other Chinese nationals linked to the Communist government and the People’s Liberation Army,” the report says. “Those associations resulted in millions of dollars in cash flow.”

According to the report, Hunter Biden’s relationship with Ye Jianming and Gongwen Dong began in 2015, while Biden's father was vice president under former President Barack Obama.

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"I think it’s very serious. The Biden family has been trading on Joe Biden’s public office for 50 years. ... Do we really think that will change if Joe Biden becomes president, the highest office in the land? If they did it when he was vice president and he was senator, of course it's going to happen when he has even more power," said Cotton, who serves on the Senate Intelligence Committee.

"Look, we know Joe Biden has misrepresented his family’s business dealings in the past. Hunter Biden flew all over the world with him. Joe Biden said they never talked about their business, Hunter Biden said they did. Emails from his laptops showed they did as well. And really on two 14-hour flights two and from China, do we really think Joe Biden never once said to Hunter Biden, 'so, what are you doing in China, son?' To borrow from one of Joe Biden's favorite phrases, come on, man."

Fox News' Hillary Vaughn contributed to this report.