US president Donald Trump told Russian officials that firing FBI director James Comey eased ‘great pressure’ on him, US media report.
The New York Times, citing a document summarising last week's meeting, says he called Comey a ‘real nut job’.
Comey had been running an inquiry into possible collusion between Russia and Donald Trump's election campaign.
The former FBI chief has agreed to testify before the Senate Intelligence Committee about the investigation.
The latest report was published just as Trump took off on a flight to the Middle East for the first leg of his first foreign tour as president.
‘I just fired the head of the F.B.I. He was crazy, a real nut job,’ Trump said, according to the report.
‘I faced great pressure because of Russia. That's taken off.’
The White House has not disputed the language used in the meeting at the Oval Office between Trump, Russian foreign minister Sergei Lavrov and the Russian ambassador Sergei Kislyak.
In another development, the Washington Post reported that a current White House official is a ‘significant person of interest’ in the investigation into alleged links between the Trump campaign and Russia.
It quoted unnamed sources familiar with the investigation as saying it was someone ‘close to the president’ but they would not identify them further. The White House has denied there was collusion between the campaign and any ‘foreign entity’.
Warning that leaks were undermining national security, White House press secretary Sean Spicer said: ‘By grandstanding and politicising the investigation into Russia's actions, James Comey created unnecessary pressure on our ability to engage and negotiate with Russia.’
‘The investigation would have always continued, and obviously, the termination of Comey would not have ended it.’
The BBC's Gary O'Donoghue, in Washington, says the White House has chosen to interpret the president's words as relating to the national interest rather than to himself.
The summary was drawn from a formal account of last week's meeting, which was attended by Russian ambassador Sergei Kislyak - a man at the centre of many of the controversial contacts between the Trump campaign and senior Russian officials.
Trump had fired Comey the evening before, a move that sent shockwaves through Washington.
Critics accused the president of trying to thwart the FBI investigation into Russia's alleged interference in the US election and any Moscow ties to Trump associates.
Comey has agreed to give details of the investigation to the US Senate Intelligence Committee at a public hearing, as well as take questions surrounding his dismissal. The date has not yet been scheduled, but is expected to take place next month.
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