Audio excerpts from a purported exchange between Italian Prime Minister Silvio Berlusconi and a call girl aired Monday on the website of the left-leaning weekly L'Espresso.
A male voice said to be Berlusconi's can be heard saying "I'm going to have a shower too. ... So wait for me in the big bed if you finish first."
A woman's voice, purportedly that of call girl Patrizia D'Addario, replies: "Which big bed... Putin's?" in an apparent reference to Russian Prime Minister Vladimir Putin.
"Putin's," the male voice says, to which the woman replies: "Oh, how sweet... the one with the curtains."
D'Addario has said Berlusconi, 72, has a four-poster bed that Putin has slept in.
The prime minister's lawyer Niccolo Ghedini scoffed at the recording, calling it "totally worthless material, totally implausible and the stuff of invention."
Anyone using the audio would be sued, he added.
D'Addario is at the centre of an investigation -- not directly implicating Berlusconi -- into an entrepreneur facing corruption charges who allegedly paid call girls to spend the night at the prime minister's Rome residence and a villa in Sardinia.
D'Addario has told the Italian media that she was promised 2,000 euros (2,800 dollars) for each of two visits.
She claims to have recorded conversations with the billionaire prime minister and handed the recordings over to investigators.
A spokesman for Berlusconi's People of Freedom party dismissed the audio segments as "a pathetic attempt to resuscitate a media campaign that has already died".
The prime minister's accusers "should just accept that and go on holiday: they obviously need to," he added.
The L'Espresso group publishes the daily newspaper La Repubblica, which has mounted a relentless campaign urging Berlusconi to explain a string of scandals that have dogged him since late April.
It has led calls for Berlusconi to explain his relationship to Noemi Letizia after his attendance at her 18th birthday party prompted his wife to file for divorce.
Every day, the newspaper publishes a set of 10 questions to the self-made billionaire, a list it updated after the call girl investigation opened.
Further fueling a media frenzy, photographs surfaced of topless young women at Berlusconi's Sardinia villa.
The flamboyant prime minister has dismissed the allegations as "all lies" and politically motivated.