If Silvio Berlusconi thought he'd shaken off the furore over his alleged use of escort girls, he was in for a nasty surprise today.

The Italian prime minister has successfully deflected and sidestepped lurid allegations about his supposed liaisons in recent weeks, helped by some timely international summitry which let him demonstrate his statesmanship, not to mention his commitment to dealing with the aftermath of the L'Aquila earthquake.

But today it was all about call girls, giant beds and the suggestion of a menage-a-trois, after a left-leaning news magazine, L'Espresso, posted "pillow talk" recordings that an escort said she made during a night with the septuagenarian Italian leader.

The escort, Patrizia D'Addario, claims the tapes relate to the night of 4 November last year, when the leaders of the world were holding their breath, waiting to see if Americans would elect their first black president.

Berlusconi, apparently, had other things on his mind.

According to D'Addario, Berlusconi was entertaining her in the bedroom of his magnificent Rome residence, Palazzo Grazioli. In one fragment of conversation, Berlusconi appears to direct D'Addario to wait for him in bed while he showers. In another conversation, recorded the next day, she protests to Giampaolo Tarantini, the businessman who allegedly set her up with the Italian prime minister, that she had not received the €5,000 (£4,300) she was expecting.

In a third snippet, it is claimed she confides to the same intermediary that Berlusconi asked her whether next time they met she would agree to a menage-a-trois with another of his girlfriends.

"He said that he has a girlfriend and would like to have me licked by this girlfriend," D'Addario says, according to the posted recordings.

The Berlusconi camp moved quickly to rubbish the tapes. Berlusconi's spokesman said: "This seesaw of gossip is not getting anywhere". A spokesman for his party, the Freedom People, called the release of the recordings "pathetic". An attorney, Niccolo Ghedini, said they were "without any merit, completely improbable and the fruit of invention".

The content of the conversations was reported in broad terms last month, but the words themselves, some pronounced in what sound like the distinctively nasal tones of Italy's prime minister, are likely to have an effect no news report can rival.

One of the conversations appears to back claims that Italy's leader has a giant bed with a connection, as yet unclear, to his Russian counterpart, Vladimir Putin.

After an exchange in which the prime minister seems to be offering a present to D'Addario, he says to her: "I'm taking a shower." He then asks her to wait on the big bed. She asks which one. He replies: "Putin's".

The tapes also include ammunition for Berlusconi's supporters, however. He has said that he has never paid for sex, and insisted that he was unaware the women who attended his parties were being rewarded. In the telephone call with Tarantini, D'Addario tells him that things went well, adding: "No envelope, though."

There is another respect in which the recordings could help Berlusconi. They imply that the 72 year-old billionaire politician, who has had prostate cancer, nevertheless has remarkable sexual endurance. It remains to be seen if that will inspire more admiration than censure among ordinary Italians.

D'Addario tells Tarantini "we didn't sleep a wink" and when Berlusconi calls her later, she is heard to say that she is not tired even though she didn't sleep. "Only my voice has gone," she says. He replies: "Why? We didn't shout."

On the recording, both the voices sound gruff.

D'Addario, who stood as a candidate in local elections this year for a group close to the prime minister's party, has given the recordings to prosecutors investigating Tarantini.

• This article was amended on 27 July 2009, to correct one of D'Addario's quotations.