ROME - The first round of voting for Italy's next president ended in stalemate with no candidate obtaining a majority of two-thirds of parliamentary votes needed.

Italian lawmakers were unable to break a deadlock which threatens to further stall incoming prime minister Romano Prodi's accession to power, a month after winning a general election.

The presidential candidate presented by the right-wing coalition, Gianni Letta, outgoing Prime Minister Silvio Berlusconi's close aide and undersecretary, received 368 votes, according to a first count.

There were 438 blank votes after Prodi said that the centre-left would leave their ballots blank, in a signal that he could not muster the votes to have his candidate elected in the first round.

Prodi, a former European Commission president, said the move was intended to show the opposition that his coalition was still open to negotiations.

Berlusconi had asked his allies to block Prodi's candidate Giorgio Napolitano, an 80-year-old senator for life and former parliament speaker.

Berlusconi's allies said Napolitano was too left-wing for the job.

"Giorgio Napolitano is an excellent candidate, and we will vote for him when the conditions will be present to elect him president. We hope that the centre-right will join their votes to ours to elect him," said Piero Fassino, secretary of the Democrats of the Left (DS) party, after the vote.

"We will see what happens tomorrow (Tuesday) and we'll decide afterwards," Fassino said.

Voting in a second round was due to start at 11:30 am (1030 GMT) on Tuesday.

More than 1,000 deputies, senators and representatives of Italy's 20 regional assemblies voted in the first round.

A two-thirds majority of 674 would have been necessary to elect a president.

More than 150 voters ignored voting orders and gave their support to people who were not on voting lists. Berlusconi received two votes and his friend, lawmaker and lawyer Cesare Previti, in prison for corrupting magistrates, received three votes.

Prodi, who under Italy's constitution cannot form a government until a new president is elected to succeed the retiring Carlo Azeglio Ciampi, may be forced to wait until a fourth round on Wednesday to ensure that his candidate, or a compromise nominee, is elected when voting is decided by a simple majority.

Napolitano emerged as Prodi's compromise candidate late Sunday after a frenzied round of party meetings designed to break a days-long deadlock.

Prodi had to drop his preferred choice, 57-year-old Massimo D'Alema, from DS, after objections from the centre-right over his communist past.

D'Alema, who is instead likely to be given a cabinet post, gave Napolitano his backing.

"Giorgio Napolitano went in a cardinal and I believe he will emerge as pope," he told Italy's Canale 5 television.

Napolitano also comes from the DS, the largest party in Prodi's coalition, a motley collection of parties ranging from Catholics to communists, which has been pressurising Prodi for a major post.

The choice of president must be a widely respected figure seen to be above party politics, such as the 85-year-old Ciampi, seen by many Italians as a grandfather of the nation. The need for Prodi to win consensus is vital, particularly as his coalition's narrow election victory split the country in two.

Berlusconi has accused the left of seeking to "occupy" the main institutional posts, having already used their tiny majority to elect left-wing speakers to both houses of parliament.

Instead, the centre-right has proposed that Prodi's coalition provide a list of four candidates, former prime ministers Giuliano Amato and Lamberto Dini, the newly elected Senate speaker Franco Marini and former EU Commissioner Mario Monti.

All have been spoken of as likely consensus candidates who may come to the fore as the voting process goes on.