President Giorgio Napolitano accepted his offer and is likely to appoint technocrat Mario Monti his successor.

Mr Berlusconi lost his majority amid an acute debt crisis that threatens the eurozone. He promised to go once MPs had approved new austerity measures.

Mr Berlusconi is Italy's longest-serving post-war prime minister. His premiership has recently been marred by many scandals.

He is a consummate survivor, our correspondent says, but he was overwhelmed by the scale of the financial crisis which has engulfed Italy.

After losing his parliamentary majority on November 8, Berlusconi promised to resign when austerity measures, demanded by the EU and designed to restore markets' confidence in the country's economy, were passed by both houses of parliament.

Members of the lower house voted 380-26 with two abstentions on November 12, a day after the Senate approved the measures that have now been signed into law.

VOV/BBC