Former FBI Director James Comey admits in a new interview that he doesn't know if the "pee tape" - one of the more salacious items in the so-called Steele dossier - exists.

The "golden showers" allegation, which first surfaced in the dossier of unverified opposition research created by former British intelligence agent Christopher Steele, claims Trump ordered two prostitutes to urinate on a bed once used by the Obamas at the Moscow Ritz-Carlton.

In excerpts from an interview airing on an ABC News "20/20" special this Sunday, Comey says that its "possible" that the alleged incident occurred and that he was careful not to tell Trump whether he believed the allegations or not.

"I honestly never thought this words would come out of my mouth, but I don't know whether the current president of the United States was with prostitutes peeing on each other in Moscow in 2013," Comey told ABC. "It's possible, but I don't know."

Comey went on to give details of his explanation of the allegations to the president, who he says reacted with shock and anger over the possibility that first lady Melania Trump might believe them.

"I started to tell him about the allegation was that he had been involved with prostitutes in a hotel in Moscow in 2013 during the visit for the Miss Universe pageant and that the Russians had filmed the episode, and he interrupted very defensively and started talking about it, you know, 'Do I look like a guy who needs hookers?'" Comey said.

"And I assumed he was asking that rhetorically, I didn't answer that, and I just moved on and explained, 'Sir, I'm not saying that we credit this, I'm not saying we believe it. We just thought it very important that you know.' "

"I never said, 'I don't believe it,' because I couldn't say one way or another," Comey said.

In his soon-to-be-released book, "A Higher Loyalty: Truth, Lies, and Leadership," Comey writes that Trump repeatedly denied the allegations in multiple conversations with his FBI chief, and considered having them investigated and proven false.

"I'm a germaphobe," Trump told Comey in a phone call on Jan. 11, 2017, according to the book. "There's no way I would let people pee on each other around me. No way."