Italians fed up with austerity went to the polls on Sunday in elections likely to be won by the centre-left, as Europe held its breath for signs of fresh instability in the eurozone's third economy.

The elections are Italy's first since billionaire tycoon Silvio Berlusconi was ousted in 2011 during a wave of financial market panic and replaced by former top European commissioner Mario Monti.

The most likely winner is the Democratic Party and its leader Pier Luigi Bersani, who says he will stick to reforms but also do more for growth as Italy endures its longest recession in 20 years.

"I am voting for the Democratic Party. I don't want us to end up like Greece," said Alessandro, a 63-year-old manager, as he cast his ballot in Milan.

But the scandal-tainted Berlusconi, a three-time prime minister who is also a defendant in two trials for tax fraud and having sex with an underage prostitute, could come a close second.

"There's a lot of confusion in these elections. I'm voting Berlusconi. I know he has his defects but he's the best," said Maria Teresa Gottardi, 65.

In third place, according to the polls, could be a new protest party led by comedian turned activist Beppe Grillo who has channelled growing social discontent and anger at traditional politicians.

"Italy votes in uncertainty," read a headline in La Stampa daily, while the Il Fatto Quotidiano said: "The undecided voters will decide it".

Polling stations close at 2100 GMT on Sunday and open again for a second day of voting at 0600 GMT on Monday, closing at 1400 GMT.

Exit polls are expected immediately after the close and preliminary official results will begin trickling through later on Monday and perhaps into Tuesday.

Officials have called on Italians to vote amid fears that general disenchantment with politics could mean a much lower turnout than usual.

Forty-seven million Italians are eligible to vote.

Voter Caterina, 19, said: "The Democratic Party are the only ones who can solve our problems."

And Sara Di Gregori, a 30-year-old lawyer in Rome, warned: "If Berlusconi returns, it would be a disaster."

Opinion polls indicate the result may not give Bersani alone a strong enough majority to rule and he may have to seek an alliance with Monti, which could bring the economics professor back into government.

A coalition between Monti and Bersani would not be simple because of the differences between the free-marketeer Monti and a small far-left party that is already in coalition with Bersani.

Berlusconi will also continue to be a powerful force. He has risen sharply in the polls with a promise to reimburse an unpopular property tax.

He has also won votes by blaming a "hegemonic" Germany for Italy's woes.

Candidates on Saturday were supposed to stay silent on the eve of the vote but Berlusconi apparently broke the rules by speaking to journalists.

In an interview with Greek television that was reported by Italian media, Berlusconi said: "I contradicted the lords of austerity who are now trying to get rid of me."

He said Monti was "subservient and always on his knees in front of Mrs Merkel (German Chancellor Angela Merkel) and now she does not want to lose him".

"I would give her a run for her money," he said.

Berlusconi was forced out in November 2011 following a parliamentary revolt, a myriad of sex scandals and a wave of panic on financial markets.

The sober Monti, a former economics professor, has brought the markets to heel and restored Italy's image as a key player in the eurozone debate.

Italy is the euro area's third largest economy after Germany and France and a major exporter.

While its debt is sky-high at around 120.1 percent of its gross domestic product (GDP) -- second only to Greece's -- its public deficit is under control.

European Parliament president Martin Schulz, a German once invited by Berlusconi to play the role of a Nazi camp guard, has urged Italians not to vote for him.

"Berlusconi has already sent Italy into a tailspin with irresponsible government action and personal capers," Schulz told the Bild newspaper.

German Finance Minister Wolfgang Schaeuble meanwhile told the Stuttgarter Zeitung that it was "in Italy's interests" to continue Monti's reforms.