* Marches in Spain, Italy, France, Greece and Portugal
* Protesters carry banners opposing budget cuts
* Greece, France to vote on Sunday
By Renee Maltezou
ATHENS, May 1 (Reuters) - Hundreds of thousands of workers across southern Europe protested against spending cuts at May Day rallies on Tuesday, before weekend elections in Greece and France where voters are expected to punish leaders for austerity.
Unions in Spain, Portugal, Italy, France and Greece used the traditional marches to express anger over a savings drive across the euro zone, aimed at shoring up public finances but criticised for forcing countries deeper into recession.
Italian demonstrators briefly clashed with police in riot gear in Turin and thousands marched in the central city of Rieti to listen to the leaders of the country's three main unions denounce Prime Minister Mario Monti's reforms.
French trade unions organised about 290 demonstrations, from Marseille in the south to Strasbourg in the east, as well as in Paris. The Interior Ministry said 316,000 people turned out altogether, compared to 77,000 in 2011.
President Nicolas Sarkozy attracted almost 100,000 to a rival Paris rally for "real workers" after the largest union, the CGT, advised members to vote him out of power on Sunday, the first time a union has openly urged a vote against a candidate.
In Madrid, tens of thousands headed in the rain to the main square waving signs opposing cuts, while thousands turned out in Lisbon. In Athens around 5,000 workers, pensioners and students marched with banners reading "Revolt now" and "Tax the rich".
Greece will vote on Sunday in a parliamentary election that risks derailing the international bailout keeping the country afloat by punishing the parties that backed the package.
"Our message will be stronger on Sunday," said Maria Drakaki, 45, a public sector worker whose salary has been cut.
"There's no way I'm voting for one of the two main parties."
In France, Sarkozy addressed a rally near the Eiffel Tower with a message to unite and work harder to pull France out of the financial crisis.
French voters seem poised to chose policies favouring economic growth over austerity with Socialist Francois Hollande leading Sarkozy in the polls. Far-right leader Marine Le Pen, whose supporters are key for the result, told her party's annual rally on Tuesday she would cast a blank vote.
DESPAIR
The marches come against a backdrop of growing frustration towards austerity that more fiscally conservative northern euro zone members say is necessary to bring deficits down to meet EU limits and end the debt crisis.
Unemployment has soared and loan defaults are on the rise. In Italy there are frequent reports of suicides as people lose their jobs or their businesses fail.
A right-wing group in the northern Emilia-Romagna region plastered posters outside several cemeteries reading "Happy May Day, workers who have committed suicide".
Protesters in Turin shouted down the local mayor as he led a parade, accusing him of not doing enough to create jobs in the city that is the home of Italian car giant FIAT.
In Portugal, thousands of people rallied in Lisbon, some with placards saying "Stop the robbery, no more stolen wages".
The 700,000-strong CGTP union, which refused to sign a pact on labour market reforms required under a 78-billion euro EU/IMF bailout this year, rallied across Portugal under the slogan "Against exploitation and impoverishment, for a policy change".
"Austerity is not a solution for Portugal or Europe," said Joao Proenca, chief of the UGT union, the second biggest. "The pivotal issue is to promote job creation."
Portugal is implementing tough austerity measures, which have deepened its recession and pushed unemployment to all-time highs of around 15 percent.
Spain's jobless rate rose to near 25 percent in the first quarter, more than double the EU average, as the economy sank into recession. Some economists, including those at the International Monetary Fund, have questioned whether deep cuts should be made at the expense of growth.
POOR GETTING POORER
In Greece, repeated rounds of cuts have slashed wages and pensions and deepened a recession that is now in its fifth year. Private sector wages shrunk by a quarter last year alone and one Greek youth in two is out of work.
"These politicians cannot help us," said Dina Bitsi, 58, a pensioner with two unemployed sons. "They approved the austerity package and the bailout. We are turning our backs on them."
The two biggest Greek parties, the Socialist PASOK and the conservative New Democracy, have ruled Greece for decades but are expected to struggle to win enough support to renew their pro-bailout coalition.
Greece's lenders have said that if the country fails to stick to the reforms pledged in return for 130 billion euros in aid, the country might be forced to abandon the euro.
Most Greeks want to keep the single currency, despite opposing the austerity measures they have been forced to endure since the country's first EU/IMF bailout in 2010.
"We want to stay in the European Union and the euro. We realise there is a crisis but it's unacceptable that even now the rich have become richer and the poor poorer," Bitsi said.