US President Donald Trump, right, and Russia President Vladimir Putin talk during the family photo session at the APEC Summit in Danang in 2017. Picture: Mikhail Klimentyev/Sputnik via AP

Washington - Copies of memos by ex-FBI director James Comey were posted online late Thursday, revealing that Russian President Vladimir Putin apparently boasted to US President Donald Trump that his country had "the most beautiful hookers in the world."

The memos document Comey's meetings and phone calls with Trump before he was fired in May, and are believed to be key to an investigation into whether the president attempted to obstruct a probe into potential collusion between his campaign team and Russia.

Redacted versions were posted online by US media after the Department of Justice handed copies over to Congress.

The move was meant to avert a legal stand-off between Deputy Attorney General Rod Rosenstein and House Republicans, who have demanded access to them, according to the news website Politico.

The partially redacted memos of former FBI Director James Comey after the US Justice Department released them in Washington. Picture: Gavino Garay/Reuters

In one memo dated February 8, 2017, Comey reports that Trump "brought up the 'Golden Showers thing'," a reference to a dossier of information on Trump put together by a former British spy and which suggested that Moscow may have compromising information on him.

Trump said it bothered him "if his wife had any doubt about" the dossier's claims that he cavorted with prostitutes in Moscow in 2013.

The partially redacted memos of former FBI Director James Comey
Picture: Gavino Garay/Reuters

"The president said 'the hookers thing' is nonsense," Comey reported, but added that Trump told him that Putin boasted to him that "We have some of the most beautiful hookers in the world."

"He did not say when Putin had told him this," Comey wrote.

Former FBI director James Comey poses for photographs at a book store in New York. Picture: Frank Franklin II/AP

Weeks earlier, however, Putin was widely reported to have told reporters in Moscow that he did not believe the contents of the dossier, although Russian prostitutes were "undoubtedly the best."

Comey, who has attacked Trump in a new book published this week, has already discussed the memos widely in public.

Picture: Gavino Garay/Reuters

Trump responded to their release by claiming that they proved he had done nothing wrong.

"James Comey Memos just out and show clearly that there was NO COLLUSION and NO OBSTRUCTION. Also, he leaked classified information. WOW! Will the Witch Hunt continue?" he tweeted.

The three House Republican committee chairmen who demanded the release of the memos agreed, saying they showed "Comey never wrote that he felt obstructed or threatened."

The documents instead illustrated that "the president made clear he wanted allegations of collusion, coordination, and conspiracy between his campaign and Russia fully investigated," Bob Goodlatte, Trey Gowdy and Devin Nunes wrote in a statement.

The partially redacted memos of former FBI Director James Comey after the US Justice Department released them.
Picture: Gavino Garay/Reuters

In another memo, dated January 28, 2017, Trump told Comey he had "serious reservations" about then national security advisor Mike Flynn's judgement.

To illustrate his point, Trump told Comey that Flynn had forgotten to tell him about a phone call from an important world leader, according to the memo.

Picture: Gavino Garay/Reuters

Trump fired Flynn days later, supposedly for lying to Vice President Mike Pence about contact he had had with the Russian ambassador during the presidential transition period.

Flynn pleaded guilty to lying to FBI agents in December, after being charged by investigators probing Russian interference in the US presidential election.