A veteran ABC journalist has lashed out at President Donald Trump, accusing him of waging a "war on the media" after a tense moment in a press pack outside the White House.

President Trump stopped to take questions at the White House on Tuesday before leaving for London on Air Force One for his second state visit to the United Kingdom.

ABC's Americas editor John Lyons asked President Trump questions for the national broadcaster's Four Corners program.

When Mr Lyons asked if it was appropriate for a president in office to be "engaged in so much business activity", the US leader snapped, asking where the reporter was from.

Mr Lyons also did not ask about any specific business dealings in his questions.

"I am from the Australian Broadcasting Corporation, Four Corners program," Mr Lyons r

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