Republican House Speaker Kevin McCarthy, bowing to pressure from his party's hard right, gave the go-ahead on Tuesday for an impeachment investigation into US President Joe Biden.

"I am directing our House committee to open a formal impeachment inquiry into President Joe Biden," McCarthy said, alleging that the Democratic president had lied to the American people about his son Hunter's foreign business dealings.

"House Republicans have uncovered serious and credible allegations about President Biden's conduct," McCarthy said. "Taken together, these allegations paint a picture of a culture of corruption."

The business dealings of Biden's son Hunter while his father was vice president under Barack Obama have been a constant target of Republicans.

No credible evidence has emerged so far, however, that the elder Biden was involved in anything illegal.

McCarthy has been under pressure from the right wing of the party, loyal to Donald Trump, for months to open an impeachment inquiry into 80-year-old Biden.

The White House immediately condemned the move, calling it "extreme politics at its worst."

"House Republicans have been investigating the President for 9 months, and they've turned up no evidence of wrongdoing," Ian Sams, White House spokesman for oversight and investigations, said on X, formerly known as Twitter.

McCarthy, who was forced to compromise with the far-right of the party to win his powerful speaker's post, said the "allegations of abuse of power, obstruction and corruption" against Biden "warrant further investigation by the House of Representatives."

Democratic lawmakers have denounced the move as a purely partisan exercise intended to exact revenge for the double impeachment by the House of former Republican president Trump.