Greeks angry at years of austerity shrugged off the risk of a euro zone exit and punished their ruling parties, which failed to win enough votes to form a ruling coalition in Sunday's election.

With about 95 percent of the vote counted, conservative New Democracy and Socialist PASOK, who have dominated Greece for decades and are the only two major parties supporting an EU/IMF bailout program that keeps Greece afloat, won less than 33 percent of ballots and only 150 out of 300 parliament seats.

In order to renew their uneasy partnership, they would have to woo other reluctant parties. Any coalition is expected to be short-lived, plunging Greece into fresh political uncertainty and threatening to revive Europe's debt crisis.

As results trickled in, New Democracy leader Antonis Samaras called for a pro-European national unity government that would keep Greece in the euro zone. PASOK leader Evangelos Venizelos also called for a unity government, saying his party had paid the price for handling the sovereign debt crisis.

The small parties that gained in the election are all against the bailout, but they are too divided to form an alternative coalition.

"There is a lot of uncertainty at the moment about what kind of government there will be and if it will be supportive of the EU/IMF program," Diego Iscaro from IHS Global Insight said.

Once mighty PASOK was pushed into third place by the anti-bailout Left Coalition party, in a stunning vote against austerity policies that have caused deep hardship in one of Europe's worst postwar recessions.

New Democracy polled just over 19 percent and PASOK a humiliating 13.4 percent, while the Left Coalition captured 16.6.

In the 2009 election, PASOK won a landslide victory with 44 percent and the Left Coalition had just 5 percent.

"I cannot take it anymore, living as beggars in our own country. The Left Coalition can shake them up, and wake them up," said Kate Savvidou, 65, a pensioner who deserted PASOK.

Left Coalition leader Alexis Tsipras, at 37 Greece's youngest political leader, hailed a peaceful revolution and said German Chancellor Angela Merkel should understand that austerity policies had been defeated.

"Greek people gave a mandate for a new dawn with solidarity and justice, instead of barbaric bailout measures," he said.

In another indication of the extent of public anger, the extreme right Golden Dawn party was poised to take nearly 7 percent of the vote. This would allow such a party to enter parliament for the first time since the fall of a military dictatorship in 1974.