A huge protest vote by Italians enraged by economic hardship and political corruption pushed the country towards deadlock after Italy’s election, with voting projections showing no coalition strong enough to form a government.
The projections suggested the centre left could have a slim lead in the race for the lower house of parliament, after more than two thirds of the vote was counted.
No party or coalition appeared likely to be able to form a majority in the upper house or Senate, creating a deadlocked parliament - the opposite of the stable result that Italy desperately needs to tackle a deep recession.
Such an outcome has the potential to revive fears over the eurozone debt crisis, with prospects of a long period of uncertainty in the zone's third largest economy.
Italian financial markets took fright after rising earlier on hopes for a stable and strong centre-left led government, probably backed by outgoing technocrat premier Mario Monti.
The projected result was a stunning success for Genoese comic Beppe Grillo, leader of the populist 5-Star Movement, who toured the country in his first national election campaign hurling obscenity-laced insults against a discredited political class.
With vague election promises and a team of almost totally unknown candidates, the shaggy haired comedian channelled pure public anger against what many see as a sclerotic and useless political system.
The likely result was also a humiliating slap in the face for colourless centre-left leader Pier Luigi Bersani, who appeared to have thrown away a 10-point opinion poll lead less than two months ago against Silvio Berlusconi's centre right.
Berlusconi, 76, who staged an extraordinary comeback from sex and corruption scandals since diving into the campaign in December, appeared to be leading in the Senate race, but Grillo's projected bloc of Senators would leave him well short of a majority.
Projections gave Bersani's centre-left alliance a lead of less than one percentage point in the lower house. If confirmed, that would be enough to control the chamber because of election laws that guarantee a 54% majority to the party with the largest share of the vote.
In the Senate the picture was different. The latest projection from RAI state television showed Berlusconi's bloc winning 112 Senate seats, the centre-left 105 and Grillo 64, with Monti languishing on only 20 after a failed campaign which never took off. The Senate majority is 158.
Berlusconi, a master politician and communicator, wooed voters with a blitz of television appearances and promises to refund a hated housing tax despite accusations from opponents that this was an impossible vote buying trick.
Grillo has attacked all sides in the campaign and ruled out a formal alliance with any group although it was not immediately known how he would react to his stunning success or how his supporters would behave in parliament.
A bitter campaign, fought largely over economic issues, made some investors fear a return of the kind of debt crisis that took the eurozone close to disaster and brought the technocrat Monti to office, replacing Berlusconi, in 2011.
The projected results showed more than half of Italians had voted for the anti-euro platforms of Berlusconi and Grillo.
Officials from both centre and left warned that the looming deadlock could make Italy ungovernable and force new elections.