ROME — A call girl who claims she spent the night with Italian Prime Minister Silvio Berlusconi has said she faced threats after the alleged encounter with the embattled premier, in a book published Wednesday.

In the memoirs of Patrizia D'Addario, "Gradisca Presidente" (Take Your Pleasure, President), she also makes more allegations about the "fateful" night of November 4, 2008, at Berlusconi's Rome residence.

D'Addario, 42, said she received threatening phone calls after spending the night with Berlusconi, and her mother was also threatened.

"At the start there were phone calls and threats... then they went for my mother," she wrote.

She also claimed she first made the allegations in the Corriere della Sera newspaper in June because "I feared for my life."

She told the paper that she had gone twice to Berlusconi's Rome residence on the promise of earning 2,000 euros (2,800 dollars) for each visit.

Berlusconi, 73, has said that he has never paid a woman for sex.

D'Addario is now at the centre of an investigation into an entrepreneur facing corruption charges who allegedly paid call girls to spend the night at Berlusconi's Rome residence and a villa in Sardinia.

She claims to have recorded conversations with the billionaire prime minister and handed the recordings over to investigators.

Giving more details about the alleged encounter with the premier, she wrote: "We are both under the duvet and I feel myself suffocating." She said the duvet was a gift from Russian Prime Minister Vladimir Putin.

Audio excerpts from a purported exchange between D'Addario and Berlusconi were broadcast in July on the website of the left-leaning news magazine L'Espresso.

The call girl said she took the decision to make the revelations public as Berlusconi did not keep his promise to help her in a real estate project that would have allowed her to stop working as a prostitute.

She also wrote in the memoirs that Berlusconi was the only politician on her books.

"I had the number one, and that is all," she wrote.