Marine Le Pen's top aide and and architect of her far-Right Front National's "detoxification" drive has stepped down in what he called a "terrifying" victory for hardliners.

Florian Philippot, one of Ms Le Pen's closest allies, said he was leaving the party a day after she stripped him of his role as FN chief strategist while allowing him to retain his title of vice president.

"They told me that I was vice-president of nothing," Mr Philippot, 35, told France 2. "Listen, I'm not into being ridiculed. I have no taste for doing nothing, so of course I am leaving the Front National."

Since its disappointing performance in both the May presidential and June parliamentary elections Mr Philippot said the FN was showing signs of taking "an absolutely terrifying backward slide" to its "old demons". The party has sought to shed its historic image as a racist, anti-Semitic party.

"I saw how things were developing negatively these past weeks, that maybe I wouldn't have a place in the project and thus they needed a pretext," he said.