Silvio Berlusconi's centre-right bloc has a clear lead ahead of Italy's parliamentary election on March 4 but is unlikely to win a working majority, a batch of final opinion polls showed on Friday, pointing to possible political deadlock.

Under Italian election rules, polls cannot be published in the final two weeks of campaigning, although they will continue to be conducted. Some 50 surveys released since December have shown no major shift in voting intentions, although more than a third of voters remain undecided.

"There are still millions of undecided voters, and there could be unexpected events, but electoral mathematics and voting trends say the most likely outcome of this election will be deadlock," Roberto D'Alimonte, a politics professor at Rome's Luiss University, wrote in Il Sole 24 Ore newspaper.

If no one party or alliance emerges victorious, President Sergio Mattarella could try to install a technocrat or coalition government with broad support in parliament, or call a new election.

Prime Minister Paolo Gentiloni, whose centre-left Democratic Party (PD) has steadily lost support and lags in the polls, shrugged off concerns about political uncertainty.

"Italy will have a government, it will have a stable government," he told a joint news conference with German Chancellor Angela Merkel during a visit to Berlin.

SURPRISE RESULT?

Under a new, untested voting system introduced last year, the next Italian government will need to have won about 40 percent of the vote for a working majority, some pollsters say, but results in dozens of marginal, first-past-the-post constituencies will prove crucial.

This leaves the door open to a possible surprise triumph for Berlusconi's bloc, which has an average of around 36 percent in seven polls released on Thursday and Friday.

The media mogul, whose Forza Italia (Go Italy!) party is running with two far-right allies, the League and Brothers of Italy, cannot personally run for office due to a 2013 tax fraud conviction. He has not yet named his candidate for premier.

The anti-establishment 5-Star Movement is the most popular single party, with 28 percent in the latest polls, but it has ruled out forming any alliance before the vote.

This week's news that some 5-Star members had failed to pay half their salary into a fund for small businesses, as required by internal party rules, appeared to have had no impact on its support.

PD party leader Matteo Renzi.

The governing PD, led by former prime minister Matteo Renzi, is on around 23 percent, the polls showed, while in a centre-left alliance with some much smaller parties it reaches roughly 28 percent, a shade behind 5-Star.

In the run-up to the ballot, the main party leaders have ruled out forming any broad coalition, of the type now taking shape in Germany, aware that opening up to such a possibility at this stage could discourage their core supporters.

However, most observers and politicians expect their stance to change after the vote.

Gentiloni, who would probably stay on as caretaker premier if the president decides a fresh election is needed, is Italy's most popular politician, with a poll in daily Corriere della Sera giving him a 47 percent approval rating, 11 points above his closest rival.