He also pledges a rewrite of the Constitution to end what he calls a "presidential monarchy" - shorthand for a radical change that would boost parliamentary power and voter control over a head of state who currently enjoys more power in his country than presidents in many other Western democracies, including the United States.

Other policies include environmental protection and increased labour rights. In the past he has proposed a 100 per cent income tax on French residents who earn over €360,000 a year.

Mr Mélenchon has also called for the debt of troubled eurozone states to be written off to allow massive new investment to spur growth.

Criticism

Mr Mélenchon is accused by detractors of cosying up to Vladimir Putin and other autocratic leaders in South America while blaming the West for most of the world's conflicts.

"He explains to us that democracy is Cuba, Venezuela, Russia," said Yannick Jadot, an ecologist who supports Socialist candidate Benoit Hamon.

"Putin is the one who validates chemical weapons massacres in Syria and an absolutely totalitarian regime in Chechnya that is the process of massacring homosexuals," he said.