French election: tens of thousands march in Paris for leftist candidate Jean-Luc Melenchon
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Mr Melenchon of the Left Front, who represents a coalition of leftist parties including the Communists, has emerged as a significant factor in the campaign just as Socialist front-runner Francois Hollande faces a resurgent threat from incumbent President Nicolas Sarkozy.

His virulent attacks on the rich, France's elite and austerity measures have struck a chord with many voters and polls this week showed him surpassing the symbolic 10 per cent mark, up four points from the start of the year, with only five weeks to go before the April 22 first round of voting.

Organisers claimed more than 100,000 people took part in the rally, held on the anniversary of the Paris Commune uprising of 1871

Decrying a France "disfigured by inequality," Mr Melenchon called for a "civic insurrection" as he addressed a sea of supporters in Place de la Bastille.

In a 20-minute speech, Melenchon outlined a programme focused on taxing the rich and financial world, boosting social spending and increasing workers' rights.

He also vowed constitutional changes enshrining the rights to abortion, to homosexual marriage and a "green rule" forcing France to protect the environment.

The latest IFOP poll released Sunday showed Mr Melenchon with 11 per cent support in the first round.

Mr Hollande, sensing a threat to his left, has suggested to left-wing voters that a vote for Mr Melenchon could hand victory to Mr Sarkozy.