PARIS - French far-right leader Marine Le Pen was convicted of embezzlement on Monday and banned immediately for five years from running for public office, in a watershed moment that will rule her out of the 2027 presidential race unless she successfully appeals beforehand.

The French court's ruling was a catastrophic setback for Le Pen, the National Rally (RN) party chief who has been a front-runner in opinion polls for the 2027 contest.

The judge also gave Le Pen a four-year prison sentence - two years of which are suspended sentence and two which will be served under home detention. She also received a 100,000-euro ($108,200) fine.

She is almost certain to appeal, and neither the prison sentence nor the fine would be applied until her appeals are exhausted. Appeals in France can take months or even years.

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But her five-year ban from running for office kicks in immediately, via a so-called "provisional execution" measure requested by prosecutors, and will be lifted only if any appeal is upheld before the election. She retains her parliamentary seat until her term ends.

There was no immediate comment from Le Pen on the ruling. Her right-hand man, RN president Jordan Bardella, said: "Today it is not only Marine Le Pen who was unjustly condemned: It was French democracy that was killed".

Bardella now looks set to become the party's de facto candidate for the 2027 election.

Le Pen, the RN and two dozen party figures were accused of diverting more than 4 million euros ($4.33 million) of European Parliament funds to pay France-based staff. They had argued the money was used legitimately and that the allegations had defined too narrowly what a parliamentary assistant does.

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Judge Benedicte de Perthuis said Le Pen had been "at the heart" of the scheme.

Since her first defeat to French President Emmanuel Macron in 2017, Le Pen had sought to soften her image, tacking her party towards the political mainstream and striving to appear as a leader-in-waiting rather than a radical opponent of the establishment.

She currently presides over the single biggest party in the National Assembly.

'Seismic political event'

Arnaud Benedetti, a political analyst who has written a book on the RN, said the five-year ban on Le Pen was a key moment in French politics that would reverberate across parties and through the electorate.

"This is a seismic political event," he said. "Inevitably, it's going to reshuffle the pack, particularly on the right."

While Bardella has helped expand the RN's appeal among younger voters, experts said it was unclear whether he has the experience to win over the broader electorate the RN needs to secure victory in 2027.

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"I am not sure that Jordan Bardella's political proposition is mature enough to be able to compete credibly in the presidential election," Benedetti said.

Matteo Salvini, Italy's deputy prime minister and head of the far-right League, strongly criticized the French ruling.

"People who are afraid of the judgment of the voters are often reassured by the judgment of the courts," he said. "In Paris they have condemned Marine Le Pen and would like to exclude her from political life."

"We will not be intimidated, we will not stop: Full steam ahead my friend!" he said.