Mr Berlusconi made the promise after Spanish newspaper El Pais published photographs of topless women and a naked man lounging at his Sardinian home. Last week, Italian prosecutors acting on a request from Berlusconi's lawyers seized the photographs and placed the photographer under investigation for alleged violation of privacy.

The photos came to light amid a scandal involving Berlusconi and Naples model Noemi Letizia, whose 18th birthday party the premier attended several weeks ago. Berlusconi's wife cited the premier's attendance at the party in announcing she was divorcing the 72-year-old.

Mr Berlusconi has denied any scandal, saying Ms Letizia is the daughter of an old friend from political circles and that he attended her birthday party because he happened to be in Naples that day. He has accused the center-left opposition of grabbing onto the gossip to try to discredit his political party before European Parliament elections this weekend.

Mr Berlusconi repeated on Friday that there was nothing 'spicy' in his relations with Letizia and said he would resign immediately if anyone could prove otherwise.

'If someone can demonstrate that the premier perjured himself, the premier would have to resign and hide himself the next minute,' he told state-run RAI radio.

Ms Letizia's ex-boyfriend has said Ms Letizia and several other young women spent a week at Mr Berlusconi's Sardinian villa over New Year's and that he listened in on phone calls between Mr Berlusconi and Ms Letizia, fueling speculation about an inappropriate relationship between the two.

Photographer Antonello Zappadu shot hundreds of photos of the party from outside the villa's gates, which were seized by Rome prosecutors. But Mr Zappadu said he had already sold the rights to the photos outside Italy, possibly explaining their publication by El Pais under the headline 'The photos vetoed by Berlusconi.'

One of the pictures features two topless women in the garden, another shows a naked man poolside, a third shows a woman in a red coat while two others show Mr Berlusconi walking in the garden. Besides Mr Berlusconi, all have their faces fuzzed over and none is identified.

Mr Berlusconi has denounced the paparazzi for what he has said was an invasion of his privacy - a charge he repeated Friday after El Pais published the photos. 'We're talking about innocent photos, but there was a violation of privacy,' he told RAI. -- AP