Tens of thousands of left-wing protesters took to the streets of Paris to denounce EU-driven austerity measures being pushed on member states, a day after similar protests in Spain and Portugal. Chanting "Resistance!", protesters marched through central Paris on Sunday in a rally organisers said was aimed at fighting EU-imposed austerity, not at criticising the government of Socialist President Francois Hollande. "This day is the day the French people launch a movement against the policy of austerity," one-time presidential contender and Left Front leader Jean-Luc Melenchon said at the march. Melenchon denied the protest was aimed at Hollande, saying: "This is a left-wing demonstration ... under a left-wing government." Organisers said 80,000 people took part in the rally. "It was very successful, beyond our expectations," said Annick Coupe, a spokeswoman for the Solidaires union. Prime Minister Jean-Marc Ayrault is set to open a debate on the fiscal pact in the National Assembly today. The pact, agreed by EU leaders in March, requires its signatories to write into law a commitment to limit structural deficits to within 0.5 per cent of gross domestic product. Many on the French left - including within the Socialists and their Green Party allies - have said they will vote against the measure, but with right-wing deputies backing the pact, it is expected to be approved. Speaking to deputies from the Radical Left Party (PRG), Ayrault said approving the pact would be an "essential step" in resolving the debt crisis threatening the euro zone and its single currency. "Francois Hollande and I will never take the responsibility ... of making the euro disappear," he said. "The future of the euro zone is at stake." Hollande's government on Friday unveiled a 2013 budget aimed at plugging the €37 billion(HK$369 billion) hole in France's public finances through tax increases and spending cuts.