Donald Trump told James Comey that Russian President Vladimir Putin had boasted to him about the beauty of his country's prostitutes, according to a memo written by Comey.

The claim was made in the notes written by the former FBI chief about his meetings with the US president.

The 15 pages of memos, obtained by the Associated Press, also reveal the president's concerns about his then national security adviser Michael Flynn.

Mr Trump's chief of staff asked days later if Flynn's communications were being monitored under a secret surveillance warrant, according to the memos.

The 15 pages of documents contain new details about a series of interactions with Mr Trump that Mr Comey found so unnerving that he documented them in writing.

Those encounters in the weeks before Mr Comey's May 2017 firing include a Trump Tower discussion about a possible encounter between Trump and prostitutes in Moscow; a White House dinner at which Comey says Trump asked him for his loyalty; and a private Oval Office discussion where the ex-FBI head says the president asked him to end an investigation into Flynn.

Reacting to the publication of the memos, Mr Trump tweeted: "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?"

The documents had been eagerly anticipated since their existence was first revealed last year, especially since Comey's interactions with Trump are part of special counsel Robert Mueller's investigation into whether the president sought to obstruct justice. The memos have been turned over to Mueller.