US House Speaker Nancy Pelosi, often sober, was upset after a reporter asked if she "hated" President Donald Trump.

"I don't hate anyone," Pelosi responded in a rare rage. "I grew up in a way that was all love and I always pray for the president," she said. "I still pray for the president."

"So don't provoke me when it comes to words like that," she said with a force that surprised the audience in the press room of the US Capitol.

Pelosi, the top Democrat in Congress, just concluded a press conference after announcing that lawmakers would go ahead with drafting articles on Trump's impeachment, when a reporter shouted whether the motive was to hate the president.

She began criticizing a reporter working for a conservative radio network, first at the edge of the podium, before returning to the loudspeaker to respond strongly to criticism.

"Do you hate the president, Madam Speaker," the reporter said, pointing out that a senior Republican lawmaker said that the process of accusing Trump of negligence was driven by strong hatred for Trump as a person.

The Democrat-controlled House of Representatives is investigating an impeachment of Trump over the latter's request from Ukrainian President Volodymyr Zelinsky last July to scrutinize the placement of Joe Biden's son, Hunter, in a Ukrainian company.

Biden is seeking the Democratic nomination to run for president next year against Trump. Trump's request is seen as an invitation to foreign parties to interfere in the US election.