In this Oct. 11, 2012, file photo, Hunter Biden waits for the start of the his father Joe Biden's debate at Centre College in Danville, Kentucky. Credit: Pablo Martinez Monsivais | AP

Hunter Biden, the son of former vice president Joe Biden, said Sunday that he will step down from his position on the board of a Chinese company, a move that comes amid escalating attacks from President Donald Trump.

In a statement released by his attorney, Hunter Biden also said he would not serve on the boards of foreign-owned companies if his father wins the 2020 presidential election.

“Hunter makes the following commitment: Under a Biden Administration, Hunter will readily comply with any and all guidelines or standards a President Biden may issue to address purported conflicts of interest, or the appearance of such conflicts, including any restrictions related to overseas business interests,” the attorney, George Mesires, said in the statement. “In any event, Hunter will agree not to serve on boards of, or work on behalf of, foreign owned companies.”

At a rally in Minneapolis on Thursday night, Trump attacked both Bidens in his most personal terms yet, highlighting unsubstantiated claims about Hunter Biden and using profanity to describe Joe Biden’s tenure as vice president.

“Hunter, you know nothing about energy. You know nothing about China. You know nothing about anything, frankly,” Trump said. “Hunter, you’re a loser.”

Mocking Hunter Biden’s lack of public appearances, Trump bellowed: “Whatever happened to Hunter? Where the hell is he? … I have an idea for a new T-shirt … Where’s Hunter?”

Hunter Biden served for nearly five years on the board of Burisma, Ukraine’s largest private gas company, whose owner came under scrutiny by Ukrainian prosecutors on suspicion of abuse of power and unlawful enrichment. Hunter Biden was not accused of any wrongdoing in the investigation.

As vice president, Joe Biden pressured Ukraine to fire the top prosecutor, Viktor Shokin, who Biden and other Western officials said was not sufficiently pursuing corruption cases. At the time, the investigation into Burisma was dormant, according to former Ukrainian and U.S. officials

In the statement released Sunday, Mesires said Hunter Biden undertook his business activities independently and “did not believe it appropriate to discuss them with his father, nor did he.”

“When Hunter engaged in his business pursuits, he believed that he was acting appropriately and in good faith,” the lawyer said. “He never anticipated the barrage of false charges against both him and his father by the president of the United States.”

Mesires added that Hunter Biden “will continue to keep his father personally uninvolved in his business affairs.”

A New Yorker article in July quoted Hunter Biden as saying that he and his father had one conversation during which they discussed his work with Burisma.

“Dad said, ‘I hope you know what you are doing,’ and I said, ‘I do,’” Hunter Biden told the magazine.

A Biden campaign spokesperson confirmed the authenticity of the Mesires statement but did not comment beyond that.

Washington Post writers Seung Min Kim and Cleve Wootson contributed to this report.