Center-left leader Romano Prodi said Wednesday he doesn't fear that his narrow parliamentary election victory will be reversed when the votes are checked as Premier Silvio Berlusconi has demanded.

Returns released Tuesday by the Interior Ministry gave the center-left a slim majority in both houses of parliament. Berlusconi, though, has refused to concede defeat and challenged Prodi's victory claim, demanding a recount.

Berlusconi said he would concede only after Prodi is confirmed the winner after all the checks are carried out on the voting, which he says was marred by "irregularities."

Prodi said that even though the margin of victory in both houses was razor-thin, "I do not fear a reversal of the results."

During a news conference at the foreign press club, Prodi again ruled out the possibility of a "grand coalition" of right and left proposed Tuesday by Berlusconi, saying it would be unnecessary since he had a majority in both houses.

"A grand coalition is not only extraneous to our program, but it happens when no majority emerges from the elections," Prodi said. "In this case, a majority came out."

The narrow victory has brought back the prospect of political instability in a country known for its revolving-door governments.

Prodi indicated he will count on the support of Italy's senators for life to ensure stability in parliament.

"They vote and they're part of the Senate," Prodi said of the legislators, a group of seven prominent Italians appointed by the president.

The votes of these highly respected Italians could prove pivotal if Prodi's forces want to push legislation through parliament, stepping in the case of defections or absences by Prodi allies and voting with the ruling coalition on confidence votes.

In the 315-member Senate, Prodi has won 158 seats; the center-right 156, and one independent was elected.

If the president gives Prodi the mandate to govern, parliament's two houses must put his coalition to a confidence vote. In addition, Italian governments also often resort to confidence votes to ensure swift passage of basic legislation.

At least one of the life senators has said he would not take part in confidence votes, while some of the others are seen as left-leaning and might aid Prodi.

The group includes Rita Levi Montalcini, who won the Nobel Prize for medicine in 1986, and Giulio Andreotti, the seven-time premier who saw his reputation tainted by accusations of aiding the Mafia. He was cleared in two trials.

Prodi said earlier that talks on choosing a Cabinet would begin in a few days.

"We already have had preliminary meetings" among allies, Prodi said in an interview with France's Europe 1 radio from his Rome headquarters. "We will reflect together and then I alone will make the decision."

It usually takes a few weeks to exhaust the procedures necessary for forming a government. In this case, the matter is further complicated because the mandate of the president of the republic, who must give the nod to a new premier, expires in mid-May, and the current president, Carlo Azeglio Ciampi, has indicated he would leave the task to his successor.

Prodi also said his government would pass a new conflict of interest law but added that it would not be to punish Berlusconi, who is Italy's richest man and the owner of a media empire that includes the country's largest private broadcaster as well as insurance, real estate and publishing interests.

Conflict of interest is "a problem that every democracy has, and the Italian democracy too must absolutely deal with it and we will," Prodi said.

Berlusconi's government has passed conflict of interest legislation stating that holding public office is incompatible with running a company but not with owning it. The center-left describes the measure as toothless and has vowed to pass stricter legislation, but has not given specifics.

In his first comments since the election Sunday and Monday, Berlusconi said: "Nobody now can say they have won."

Prodi responded that the remarks were "out of line."

Official results released Tuesday by the Interior Ministry gave the center-left a narrow majority in both houses of parliament. But Berlusconi has alleged irregularities and challenged Prodi's victory claim.

On Wednesday, several ballot boxes carrying the symbol of the Interior Ministry were found in a garbage can. The ANSA news agency said the ballots had been filled out and their results communicated to the Interior Ministry.

Berlusconi, speaking of the vote of Italians abroad, which proved decisive in assigning the Senate, said "there are many irregularities and therefore it's possible that this is not a vote we can say is valid."

Prodi can count on a comfortable majority in the lower house of parliament, the Chamber of Deputies, despite the narrowest of winning margins — 49.8 percent for his coalition, compared with Berlusconi's 49.7 percent. Thanks to a new, fully proportional electoral system pushed through by the conservatives against the center-left's opposition, the winning coalition in the lower house gets at least 340 deputies, or 55 percent of seats, regardless of the margin of its victory.

But with a margin of about 25,000 over the 38 million votes cast, Berlusconi called for a recount.

Prodi, a former premier and European Union chief, claimed victory Tuesday while the count was still under way, and vowed he would form a strong government able to run a country mired in zero-percent economic growth and almost evenly divided politically.

With a high voter turnout of about 84 percent, analysts talked of a deeply split country, and expressed uncertainty over what might happen next.

Berlusconi became Italy's longest serving premier since World War II thanks to his five years in power. Despite a tumultuous tenure, the conservative media mogul delivered a sense of stability to the country.

Even if the result is confirmed, long-term prospects for Prodi look problematic, and many fear a return of the ungovernability that characterized postwar Italy. There have been 60 governments in about as many years since the end of the war.

Prodi's coalition is seen as unwieldy because it built on two mainstream parties, but also includes a group of smaller formations ranging from Catholics to communists.

Prodi said negotiations in parliament on choosing Ciampi's successor would begin soon. He met with the president for over an hour Wednesday.