ATHENS (AFP) - A fire-bomb attack on an Athens bank killed at least three people Wednesday, casting a pall over a Greek general strike and fuelling market fears that the protests could derail a massive bailout plan.

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Hooded youths hurled petrol bombs at stores and businesses in the centre of the Greek capital and demonstrators tried to storm parliament, as the rioting spread to second city Thessaloniki and the country ground to a standstill.

Police said two women and a man were known to be dead in the burning bank, a branch of the Marfin group, while firefighters said some 20 people who were inside when it was attacked were evacuated.

At least five people were wounded in the bank and two government buildings were also on fire after firebomb attacks, officials said, as thousands defied the government's resolve to drive through cuts to avoid fiscal meltdown.

After rallying in two separate demonstrations in central Athens, members of the main unions began converging on parliament, where the government was preparing for the measures to be voted on Thursday.

"They're taking everything from me, I don't know how I'm going to get by," said 61-year-old Anargyros Bizianis, a municipal worker in the Athens suburb of Piraeus who earns 900 euros (1,160 dollars) a month.

As the protestors tried to break through a police line in front of the parliament, they first hurled stones and bottles of water, prompting the riot squad officers to fire back with tear gas.

Full-scale clashes soon erupted outside the building, with riot police trying to disperse the crowds with baton-charges.

Pushed to the brink of default, the Greek government agreed at the weekend to slash spending and hike taxes in return for 110 billion euros (143 billion dollars) in loans over three years from eurozone countries and the IMF.

But fears have spread from Europe and Wall Street to Asia that the bailout will not be enough to stop its debt crisis spreading to heavily indebted Spain and Portugal, sparking heavy losses on world financial markets.

The euro meanwhile slumped below 1.29 dollars on Wednesday -- striking the lowest level for more than one year -- as fallout from Greece's debt crisis showed signs of infecting the eurozone.

The IMF and eurozone countries and agreed after months of hesitation to lend Greece billions at below market rates as concerns soared that its debt crisis could trigger a knock-on effect elsewhere.

International Monetary Fund chief Dominique Strauss-Kahn admitted Wednesday there was a risk "contagion" could engulf other weakened European economies.

"There are always risks," Strauss-Kahn said. "We must avoid contagion, and that is also what the Greek plan was tailored to do," he said. "We must nevertheless all remain extremely vigilant."

Europe's main stock markets were down only slightly nearing the half-way stage on Wednesday, though losses were bigger in Athens and Madrid.

London's benchmark FTSE 100 index was down 0.03 percent at 5,409.42 points, as investors there were also awaiting Britain's general election on Thursday.

Frankfurt's DAX 30 slid 0.05 percent and the Paris CAC 40 shed 0.07 percent.

Athens dropped 0.68 percent and Madrid lost 0.69 percent as both indices pulled back from initial sharp falls.

Market analyst Patrick O'Hare of Briefing.com warned that "European officials have more to do to prove that they have the resolve to keep Greece's problems from spreading."

"The market is literally not buying the notion that the 110 billion euro aid package for Greece is a panacea," he said.

"We don't know what political and financial authorities can do to calm things down, given the current feeling of panic on the markets," bond strategists at French bank BNP Paribas said in a note.

German Chancellor Angela Merkel hit out at accusations of foot-dragging before finally agreeing to lend Greece 22.4 billion euros, saying the EU's future and Germany's role in it were "at a crossroads" and that the bloc's rules had to be changed.

"A good European is not necessarily the one who helps quickly. Much more it is someone who sticks to European treaties and national laws and who makes sure that the stability of the eurozone and of all of Europe sustains no damage."