Washington, May 20 (IANS): US President Donald Trump has told senior Russian officials that his abrupt firing of FBI Director James Comey had eased "great pressure" on him from the probe over his campaign's ties with Russia, a media report said.

A report in The New York Times quoted a White House-leaked file summarising the meeting with Russian officials.

"I just fired the head of the FBI. He was crazy, a real nut job," Trump has reportedly told Russian Foreign Minister Sergey Lavrov and Russian ambassador to the US Sergey Kislyak in the Oval Office on May 10, the day after he dismissed Comey, according to the document.

The New York Times said the document, which was based on notes taken from inside the Oval Office and has been circulated as the official account of the meeting, was read to the newspaper by a US official.

Afterwards, a second official confirmed the broad outlines of the discussion, Xinhua reported.

"I faced great pressure because of Russia. That's taken off," Trump was quoted as saying.

"I'm not under investigation," the US president told Russian officials.

Sean Spicer, the White House press secretary, did not dispute the account, only stressing that the ousted FBI chief had put unnecessary pressure on the president's ability to conduct diplomacy with Russia on matters such as Syria, Ukraine and the extreme terror group Islamic State.

"By grandstanding and politicising the investigation into Russia's actions, James Comey created unnecessary pressure on our ability to engage and negotiate with Russia," Spicer said.

"The investigation would have always continued, and obviously, the termination of Comey would not have ended it. Once again, the real story is that our national security has been undermined by the leaking of private and highly classified conversations," said Spicer.

Trump was using a negotiating tactic when he told Russian officials about the "great pressure" he was under, another US official defended the president to the Times, suggesting that Trump's purpose was to create a sense of obligation with Russian officials and to coax concessions on certain issues.

Trump is set to embark on his first overseas trip on Friday afternoon. The eight-day journey includes visits to Saudi Arabia, Israel, Italy and Belgium. The White House said earlier that Trump will not pick new FBI director nominee before he leaves the country.

On Thursday, Trump lashed out over the appointment of former FBI director Robert Mueller as the special counsel to probe Trump-Russia ties, saying that it "divides country". He said he had never colluded with Russia.

"I believe it hurts our country terribly, because it shows we're a divided, mixed-up, not-unified country," Trump said.