US President Donald Trump has said he would see nothing wrong in accepting damaging information on a 2020 political opponent if it were offered to his re-election campaign by a foreign government.

Key points: Donald Trump likened accepting dirt from foreign governments to opposition research

Donald Trump likened accepting dirt from foreign governments to opposition research He said political campaigns did not need to report suspicious foreign communications

He said political campaigns did not need to report suspicious foreign communications His Democratic challengers slammed the comments as welcoming election interference

Asked in an interview with US television network ABC News if he would accept information from Russia or China or alert the Federal Bureau of Investigation (FBI), Mr Trump said: "I think maybe you do both. I think you might want to listen. There's nothing wrong with listening.

"If somebody called, from a country — Norway — we have information on your opponent. Oh, I think I'd want to hear it."

Mr Trump's remarks to the American broadcaster drew outrage from Democratic politicians and presidential candidates seeking to challenge him in 2020, as well as one of his leading Republican allies.

"What the President said last night shows clearly, once again, over and over again, that he does not know the difference between right and wrong," US House Speaker Nancy Pelosi — the top Democrat in Congress — said.

"There is no sense … any ethical sense that informs his comments and his thinking."

Republican senator Lindsey Graham joined Democrats in criticising the President's remarks.

"I think it's a mistake," he said.

Mr Trump's son, Donald Trump Jr, was questioned by a US Senate committee on Wednesday in a closed session about a June 2016 meeting at Trump Tower in New York where a Russian lawyer had offered damaging information on Hillary Clinton, the elder Trump's Democratic opponent in the 2016 presidential election.

The meeting was a focus of US special counsel Robert Mueller's probe of Russian meddling in the last presidential campaign.

The investigation did not establish a criminal conspiracy between Russia and the Trump campaign, though Mr Trump repeatedly praised WikiLeaks in 2016 and celebrated information exposed by Russian hackers.

Donald Trump Jr's involvement in a meeting where a Russian lawyer offered dirt on Hillary Clinton has been closely scrutinised. ( Reuters: Layne Murdoch )

'Life doesn't work like that'

During the interview, Mr Trump also said he disagreed with FBI director Christopher Wray, who told US Congress last month that political campaigns should contact the agency about any suspicious communications from a foreign government.

"The FBI director is wrong," the President said. "Life doesn't work like that."

Mr Trump compared dirt on an opponent supplied by a foreign government to opposition research conducted by all political campaigns.

"[If] you go and talk honestly to congressmen, they all do it. They always have. And that's the way it is. It's called 'oppo research'."

One of Mr Trump's challengers, former vice president Joe Biden, tweeted: "President Trump is once again welcoming foreign interference in our elections.

"This isn't about politics. It is a threat to our national security.

"An American president should not seek their aid and abet those who seek to undermine democracy."

Several of Mr Trump's other Democratic opponents in the 2020 race, including Senators Elizabeth Warren and Bernie Sanders, repeated their calls to begin impeachment hearings.

Mr Trump's comments came just a month after he pledged not to use information stolen by foreign adversaries in his 2020 re-election campaign and insisted he had not used such information to his benefit in 2016.

ABC/wires