US President Donald Trump calls on China -- as well as Ukraine -- to go after his election rival Joe Biden
US President Donald Trump calls on China -- as well as Ukraine -- to go after his election rival Joe Biden AFP / Jim WATSON

President Donald Trump on Thursday said China, as well as Ukraine, should investigate his current main 2020 election rival Joe Biden.

Trump, who faces an impeachment inquiry over allegations that he pressured Ukraine to interfere in the election by attacking his opponent, told reporters he would "certainly" think about asking China to do the same.

"It's certainly something we can start thinking about," the president said of asking China to get involved.

Trump also doubled down on his earlier, hugely controversial request that Ukrainian President Volodymyr Zelensky investigate Democratic frontrunner Joe Biden and his son Hunter.

"If they were honest about it, they'd start a major investigation into the Bidens. It's a very simple answer. They should investigate the Bidens," he said at the White House.

"Likewise, China should start an investigation into the Bidens because what happened in China is just about as bad as what happened with Ukraine."

According to Trump, the Bidens were involved in corrupt deals both in Ukraine and China. However, charges have never been filed and there appears to be little in the way of evidence for the allegations.

It is illegal to ask for foreign help in a US election.