Hunter Biden breaks silence, defends his work in Ukraine and China

Hunter Biden has announced he will step down from the board of directors of a Chinese-backed private equity firm at the end of the month.

Then US Vice President Joe Biden (R) tours a Hutong alley with his son Hunter Biden (L) in Beijing, China, 05 December 2013. Source: AAP

The son of former US vice president Joe Biden has defended his work in Ukraine and China after sustained criticism from President Donald Trump which has embroiled the White House in an impeachment inquiry.

Hunter Biden has broken his silence and says through his lawyer he is stepping down from the board of a Chinese company that has been the subject of criticism from Trump and his allies.

He added he would not work for a foreign-owned company if his father is elected president in 2020.

"Hunter undertook these business activities independently," his lawyer George Mesires said in a statement on Sunday.

"He did not believe it appropriate to discuss them with his father, nor did he."

Mr Trump's accusations against Hunter Biden - which he has levied without any evidence - and his efforts to get officials in Ukraine to investigate, led Democrats in the US House of Representatives last month to begin an impeachment inquiry into the president.

Democrats assert Mr Trump risked US national security when he withheld aid to Ukraine while simultaneously pressing the country to investigate the Bidens for his own political gain.

File photo of Joe Biden's son, Hunter Biden Source: AAP

The president's allies sought to paint Hunter Biden's departure from the Chinese board as evidence of an admission of wrongdoing.

"He should have done this quite a while ago," senior White House aide Kellyanne Conway said on Fox News Business.

"In fact, he probably shouldn't have been on the board to begin with."

The most recent bout of attacks from Mr Trump have focused on Hunter Biden's work on the board of BHR (Shanghai) Equity Investment Fund Management Company, a Chinese firm that was founded to spend Chinese investment capital outside the country.

Hunter Biden invested about $US420,000 ($A618,648) in the company to obtain an equity stake, but has received no profit since then, according to his lawyer.

Hunter Biden intends to step down from the board by October 31, according to the statement. He did not give a reason for his decision to leave the board.