US President Donald Trump has said he "did not make" and does not have any recordings of his private conversations with ousted former FBI director James Comey.
"With all of the recently-reported electronic surveillance, intercepts, unmasking and illegal leaking of information," Mr Trump said he has "no idea" whether there are "tapes" or recordings of the two men's conversations.
However, he declared he "did not make, and do not have, any such recordings".
The tweets are the latest chapter in a high-stakes guessing game after Mr Trump hinted he might have recordings of his private conversations with Mr Comey at the White House and over the phone.
The tale of mystery began last month just days after Mr Trump fired Mr Comey, who was then leading an investigation into contacts before and after the election between the president's campaign and Russian officials.
The absence of recordings almost certainly elevates in significance to investigators the notes made by Mr Comey right after the conversations.
A New York Times report cited two unnamed Comey associates who recounted his version of a January dinner with the president in which Mr Trump asked for a pledge of loyalty.
Mr Comey declined, instead offering to be "honest".
When Mr Trump then pressed for "honest loyalty", Mr Comey told him, "You will have that", the associates said.
Mr Trump tweeted the next day that Mr Comey "better hope that there are no 'tapes' of our conversations before he starts leaking to the press!"
Mr Trump's tweets on Thursday raised questions about why the president would have staked his reputation and political capital on promoting something that was not real.
His earlier suggestion about tapes immediately evoked the secret White House recordings that led to Richard Nixon's downfall in the Watergate scandal.
Under a post-Watergate law, the Presidential Records Act, recordings made by presidents belong to the people and can eventually be made public. Destroying them would be a crime.
Mr Comey says any recordings that might exist would support his version that Mr Trump asked him to pledge loyalty and urged him to drop the investigation into the president's former national security adviser.
"Lordy, I hope there are tapes," Mr Comey declared at a congressional hearing.
The president has steadfastly refused to clarify whether any tapes existed.
Two weeks ago, he teased reporters in the White House rose garden by saying that he would explain "maybe some time in the very near future".
He cryptically added: "You are going to be very disappointed when you hear the answer."
White House deputy press secretary Lindsay Walters said on Wednesday that an answer would be provided this week, presumably by the Friday deadline set by the House intelligence committee for turning over any tapes.
The Secret Service had said it had no audio copies or transcripts of any tapes recorded within Mr Trump's White House, according to a freedom of information request submitted by The Wall Street Journal.
That did not exclude the possibility that recordings were created by another entity.