ROME (AFP) - Italy was at an impasse Tuesday after an election seen as crucial for the eurozone failed to produce a clear winner and provided a shock debut for a populist anti-austerity party, rattling world markets and setting off alarm bells across Europe.

Italian stocks plunged and borrowing rates jumped after centre-left Democratic Party leader Pier Luigi Bersani scraped a razor-thin victory in the lower house of parliament and the Senate ended up with no political force winning a majority.

Bersani warned Italy was in “a very delicate situation” as the political gridlock became clear late on Monday and he was due to address the growing sense of crisis later on Tuesday.

Stock markets in Europe, Asia and the United States also fell on fears of instability in the eurozone’s third biggest economy as political analysts predicted either an unsteady coalition government or fresh elections within months.

A majority in both chambers of parliament is required to form a government, leaving Italy in a state of limbo with a hung parliament that is unprecedented in its post-war history.

Under the constitution, parliament has to meet 20 days after an election at the latest, after which formal negotiations begin with Italian President Giorgio Napolitano on forming a government.  European capitals were quick to voice concern. “It’s a leap into the unknown, which bodes poorly both for Italy and for the rest of Europe,” Spanish Foreign Minister Jose Manuel Garcia Margallo said. The European Commission said it had heard “the message of concern” from Italian voters but expected the country to stick to its pledges of budget cuts and economic reforms.

“Italy has made commitments,” Commission spokesman Olivier Bailly said at a news conference. “As far as we are concerned these commitments remain.” Silvio Berlusconi’s coalition came a close second in the vote for the lower house, winning 29.18 percent of the vote to 29.54 percent for Bersani.

A third force - the populist, anti-government Five Star Movement (M5S) of former comic Beppe Grillo - won big, reaping a resounding protest vote from an electorate fed up with austerity policies and a grinding recession to score 25.5 percent in the lower house.

“We’re not against the world,” Grillo told reporters on Tuesday.

“We’ll see reform by reform, law by law. If there are proposals that are compatible with our programme, we will evaluate them,” he said.

European powerhouse Germany, as well as France, also reacted nervously, with German Foreign Minister Guido Westerwelle calling for a new government to be formed “as quickly as possible”. “The politicians in Rome know that Italy still needs a policy of reform, a policy of (budgetary) consolidation,” he said. But analysts had a mostly pessimistic outlook.

“The country which most needs stability will not have a government that lasts for more than a few months,” said James Walston, professor of international relations at the American University in Rome.

Stefano Folli, a columnist for the Il Sole 24 Ore business daily, said the only two options were a left-led “equilibrium government” that would rely on Grillo votes in the Senate or a right-left interim majority to pass key reforms and then elections within a few months.

The latter, he said, was “more realistic”. Roberto D’Alimonte, political science professor at Rome’s LUISS University, said: “Grillo will play a decisive role. He has to decide whether to strike a limited agreement with the left or go for fresh elections.”

The big loser was outgoing prime minister Mario Monti, who was drafted to run a technocratic government in the debt-strapped country after Berlusconi was ousted at the height of the financial crisis in 2011. In contrast to Grillo’s shock success, Monti won just 10.56 percent in the lower house, the Chamber of Deputies. While he won praise in Europe, he was increasingly criticised at home for his austerity measures.

“The real Italy has expressed all its malaise and in this vote can be heard the voices and the stories of those who cannot find work, who cannot retire... those who think they have no future and flee abroad,” wrote the daily La Stampa. “Boom for Grillo, Italy Ungovernable”, screamed the headline in the leftist La Repubblica daily.