The center-right coalition of Italy's Prime Minister Silvio Berlusconi suffered a heavy defeat Monday in local elections in the two main cities of Milan and Naples, seen as a key test of the premier's popularity.

In Milan, Berlusconi's hometown which was led by a center- right mayor for the past 20 years, the candidate of the largest opposition group Democratic Party (PD) Giuliano Pisapia was elected mayor.

With all votes counted, Pisapia, an attorney, won 55.10 percent of ballots, beating conservative incumbent Mayor Letizia Moratti, who took 44.89 percent. "We seem to have freed Milan,"local newspaper Corriere della Sera quoted the newly elected mayor as telling supporters who greeted him with a standing ovation upon his victory.

Italians voted on Sunday and Monday in several major cities and provinces where no candidates won more than 50 percent in a first round of voting two weeks ago.

In Arcore, outside Milan, where Berlusconi has his main residence, the center-left candidate Rosalba Colombo was elected mayor by a margin of more than 13 percent.

The center-left candidate also won in Naples, where prosecutor Luigi De Magistris became mayor. One of his first challenges, he said soon after the victory, will be to end the southern city's chronic garbage crisis, a problem compounded by the Naples mafia' s grip on waste disposal in the area.

"We have lost, it is evident," Berlusconi said after the elections results, but he insisted that defeat will not lead to his resignation or a collapse of the government. "I am a combatant, every time I lose I triple my strength," he added.

Berlusconi, 74, is on trial for four cases linked to allegations of bribery, tax fraud, and paying for sex with an underage prostitute. He denies any wrongdoing and accuses magistrates of waging a political war against him.

According to Corriere della Sera, the victory of the opposition candidates in the mayoral races show Berlusconi has fallen out of favor with Italians, who are tired of the scandals that many associate with his three-year-old government.