Marine Le Pen, the leader of France's far-right Front National, is expected to face charges of incitement to racial hatred in France after the European parliament voted to lift her parliamentary immunity.

The French state prosecutor in Lyon had asked the European parliament to lift Le Pen's protection from prosecution as an MEP so she could face charges over a speech in 2010 in which she likened Muslim street prayers to the Nazi occupation of France.

The case threatens to upset Le Pen's careful public relations strategy since taking over the party from her father, Jean-Marie Le Pen. She had sought to project a modern, more palatable face of the far-right in France, free from the type of comments about the second world war and Holocaust denial that resulted in her father being convicted of contesting crimes against humanity.

Marine Le Pen, who has been an MEP since 2004, this week called herself a dissident who was being pursued for political reasons for a "crime of opinion" and said she stood by her comments.

In December 2010 during her party's internal leadership campaign she made a speech in Lyon that denounced Muslims holding prayers in the streets, at a time when a lack of mosques in France had forced many to pray outside.

She likened the outside prayers to an occupation and added: "For those who like to talk about world war two, to talk about occupation, we could talk about, for once, the occupation of our territory. There are no armoured vehicles, no soldiers, but it is an occupation all the same, and it weighs on people."

Previously she had said of street prayers: "Very clearly, like in 1940, some think that they can behave in France in 2010 like an occupying army in a conquered country."

On Monday on French TV she repeated her comments about occupation, saying she was being targeted "for having dared to say what all French people think, that street prayers – which I must add continue to happen on French territory – are an occupation". But she did not explicitly evoke the second world war parallel.

The Front National is currently at a high in the opinion polls, after a strong score in a byelection in Villeneuve-sur-Lot in south-west France, where the party knocked out the Socialists and scored 46% of the vote in the final round.

A recent poll for YouGov about voting intentions in the European parliament elections next year put the Front National on 18%, one point behind the traditional rightwing UMP and ahead of the Socialist party. The party is hoping for gains in the French local elections next year.

After the European parliament stripped Le Pen's immunity with a show of hands by members, the Front National said it was a sign of the "growing fear of the oligarchy" faced with "the irresistible rise in power" of the far-right party in France.

Members of the European parliament have immunity from criminal and civil liability for opinions expressed as part of their duty, although immunity had been lifted in a number of cases previously.

Le Pen said she had been targeted because she was a "political adversary" and vowed to defend herself. She suggested she was proud of losing immunity, which was like getting a "medal pinned to my jacket".

If found guilty of inciting racial hatred, Le Pen would face a maximum penalty of a year in prison and a €45,000 fine.