French president warns of threat from parties such as National Front as poll on EU elections in May puts all extremists ahead

The French president, François Hollande, has warned that Europe risks "regression and paralysis" if Eurosceptics and nationalists gain the upper hand in next year's European parliament elections, as an opinion poll for the first time put the anti-immigrant National Front (NF) well ahead of his country's mainstream parties.

The Ifop poll in the newspaper Le Nouvel Observateur gave Marine Le Pen's National Front 24% in the European contest, five points ahead of Hollande's socialists and almost four times what the far-right party achieved in the last European election, in 2009.

The boost to the extreme right in France came amid growing fears among the European Union elite that extreme parties of right and left would make a strong showing in the European elections in May.

Nigel Farage's UK Independence party is tipped to do well, possibly becoming the biggest British party in the European parliament, while Geert Wilders, the Dutch anti-immigrant and anti-Islam populist, is also running strongly in the opinion polls.

German analysts and politicians expect the new anti single European currency party, Alternative for Germany, to win its first seats in a national poll. The far-right in Poland, Austria, Hungary and Bulgaria would also register gains, on current projections.

"Next May the European parliament could be for a large part composed of anti-Europeans. It would be a regression and a threat of paralysis," Hollande warned.

In remarks clearly aimed at the National Front at home but also pointing to the wider problem in Europe after four years of financial crisis, Hollande warned of the twin threat to Europe from the forces of "nationalism and populism".

He said: "Let's be honest, Europe is associated – wrongly it has to be said – with the opening of borders and thus to immigration. Nationalism springs from a lack of perspective and a collective dynamic, add in the fear of decline, with certain countries painfully living the confrontation with globalisation."

He ascribed the growth of nationalism to "relations with Islam", as well as "working people's fears faced with industrial reorganisation", the "fear of emerging countries", and "conservatism linked partly with ageing of the population".

The president added: "Xenophobia does the rest."

The Ifop pollsters found that 24% of the 1,893 French voters questioned intended to vote for the NF in next year's European elections, while 22% said they would vote for the centre-right Union for a Popular Movement, and only 19% for the governing Parti Socialiste.

In the last European elections, in 2009, the National Front took 6.34% of the vote. Pollsters stressed that the new survey reflected voters' intentions rather than a ballot prediction.

"For the first time in a poll on voting intentions in an election of a national character, the NF is clearly ahead," an Ifop spokesperson said.

A former European government minister in close contact with France's socialist leadership said Hollande's entourage was "very scared" and expected Le Pen to emerge as the winner. "This is a wake-up call from Hollande. He is right. The next European elections will bring a big victory for nationalist populists of right and left."

Others cautioned that with the ballot almost eight months away, it was too early to say. The gains for the far-right are also mirrored by gains for the hard-left in parts of Europe. The socialists in the Netherlands could make gains and the communist party in the Czech republic is expected to do well in national elections this month and could enter coalition government for the first time since the collapse of communism in 1989.

In crisis-ravaged Greece, the leftwing Syriza movement is expected to do well. In Germany, following last month's general elections, the far-left Die Linke, composed of disaffected social democrats and former East German communists, is now the third force in parliament, supplanting the Greens.

Other factors combine to suggest a strong opportunity for anti-Europeans of the far-right and hard-left. The European elections often serve as a surrogate mid-term ballot on, and protest against, sitting governments. Voter turnout is extremely low but the fringe parties are more likely to mobilise support. Beyond Germany there is a broad mood of anti-incumbency across Europe.

The boost for the French far-right comes just 10 days before the second round of a cantonal byelection in the town of Brignoles, in the Var region of southern France. The NF candidate took a stunning 40.4% of votes in the first round.

Alain Delon, one of France's most celebrated actors, voiced his support for the NF, saying he approved of the party's rise.

In an interview with the Swiss paper Le Matin, Delon said: "For years Le Pen father and daughter have fought, but they've fought somewhat alone. Now, for the first time, they're not alone. The French are with them."

The NF has been slowly gaining political ground in France since 2011 when Marine Le Pen took over at the helm of the party founded in 1972 by her father, Jean-Marie Le Pen, and known for its xenophobia and Holocaust-doubting rhetoric.

Steeve Briois, the NF secretary general, said: "The French are showing a wish to take their destiny into their hands and give back their country its sovereignty." He promised an "unprecedented earthquake" in the European elections.

Jean-Yves Camus, who is based at the Institute of International and Strategic Relations, in Paris, and is an expert on the European far-right, said: "All the ingredients are coming together for the NF to achieve a higher score than ever before in both the municipal and the European elections next year.

"The European elections will be a chance for people to express their discontent with everything associated with Europe, globalisation, outsourcing and so on."