ROME: The daughter of Italian Prime Minister Silvio Berlusconi on Friday defended her father against what she described as "disgraceful" attacks.

In an interview with the newspaper Corriere della Sera, Marina Berlusconi came out in support of her father who has been beset by a string of lurid allegations since his second wife Veronica Lario announced in May she would divorce him after he attended a young model's 18th birthday.

"I know perfectly how precious freedom of the press is ... but all freedom has a limit, which is respect of freedom of others. Journalists are free, Berlusconi is also. He is free to have a private life," she said.

"There have been real attempts to stab him in the back, but happily he has good reflexes," added Marina, who is Berlusconi's daughter by his his first wife Carla, and president of Fininvest, the holding company that controls her father's media empire Mediaset.

The prime minister and the girl whose 18th birthday he attended have vehemently denied that they had a sexual relationship.

Berlusconi has also insisted that he has never paid for sex.

On Thursday, Berlusconi, who was holding bilateral talks with his Spanish counterpart Jose Luis Rodriguez Zapatero in Sardinia, attacked journalists and repeated his denial that he had ever paid for sex.

"He is under pressure as never before. He is seeking for a way of counter-attacking," said Giacomo Marramao, professor of political philosophy at the University of Florence.

Despite the scandals of recent months, Berlusconi's popularity remains high and he has no rival, according to Marramao and French political scientist Marc Lazar.

"Berlusconi's power comes from the fact that those who want to challenge his power do not know how to act..." said Marramao.

Lazar and Marramao said the real danger for Berlusconi was a decision by the Constitutional Court on the so-called Alfano law which gives immunity to the state's four highest officials.

"It is his obsessive fear, the only things which could destabilise him," said Lazar.

"He is aggressive, wounded," said Marramao, adding that he feared he would do something "risky like an institutional rupture" if the the court ruled that the Alfano law was unconstitutional.