LONDON — Members of the European political elite expressed alarm Monday over the strong showing in European Parliament elections by nationalist and anti-immigrant parties skeptical about European integration, a development described by the French prime minister as an “earthquake.”

In France, Britain and elsewhere, anti-immigrant parties opposed to the influence of the European Union emerged in the lead. In France, the National Front won 26 percent of the vote, defeating the governing Socialists and the Union for a Popular Movement, the center-right party of former President Nicolas Sarkozy.

In Britain, the triumph of the U.K. Independence Party, which won 28 percent of the vote, marked the first time since 1910 that a nationwide vote had not been won by either the Conservative or Labour parties.

“The people’s army of UKIP have spoken tonight and delivered just about the most extraordinary result that has been seen in British politics for 100 years,” said Independence Party leader Nigel Farage.

Official results showed that populist parties strongly opposed to the EU also trounced establishment forces in Denmark and Greece and did well in Austria and Sweden.

The radical leftist Syriza coalition in Greece beat the party of Prime Minister Antonis Samaras, while Golden Dawn, a nationalist, purportedly neo-Nazi outfit that the Greek authorities have tried in vain to outlaw, also picked up seats in the European Parliament.

With the political landscape redrawn across Europe, some politicians, notably Nick Clegg, the British deputy prime minister and leader of the Liberal Democrats, the junior coalition partner, faced calls from their party members to quit. The Liberal Democrats finished fifth in Britain and lost nearly all their seats at the European Parliament.

In Spain, the two main parties failed for the first time to get a combined 50 percent of the votes. Such was the upheaval that Alfredo Perez Rubalcaba, the leader of the Socialist Party, announced Monday that he would step down after failing to capitalize on Spain’s economic woes and record unemployment to beat the governing Popular Party.

The Socialists apparently lost votes to other left-leaning parties, as well as to new groups led by Podemos, or We Can, a movement that was formed only a few months ago to oppose austerity cuts and demand fairer wage distribution. Traditional parties sought to depict the ballot as a protest vote inspired by deep alienation among voters repelled by what they consider to be out-of-touch political elites at home and an arrogant EU bureaucracy spreading its influence with no democratic mandate.

In Paris, the victory by the National Front, led by Marine Le Pen, prompted Manuel Valls, the French prime minister, to acknowledge: “It’s an earthquake.

“We are in a crisis of confidence,” Valls added.

President Francois Hollande of France called an emergency meeting of senior ministers after his Socialist Party finished a remote third. The rise of the right had been widely forecast, but it nonetheless sent shock waves. In Germany, Foreign Minister Frank-Walter Steinmeier expressed dismay over the French result and the fact that the extremist, anti-immigrant National Democratic Party of Germany, which won 1 percent of the vote, had secured a seat in the Parliament.

“In some countries, it won’t be as bad as had been feared, for example in the Netherlands, but France’s National Front is a severe signal, and it horrifies me that the NPD from Germany will be represented in the Parliament,” Steinmeier said, according to Agence France-Presse. In the German vote, traditional parties were clear winners, but a new anti-EU party, the Alternative for Germany, also took 7 percent of the vote, news reports said.

Jose Manuel Barroso, the departing president of the European Commission, the executive branch of the 28-nation EU, issued a statement Monday urging a “truly democratic debate” to meet the concerns of “those who voted in protest or did not vote.”

Information for this article was contributed by Raphael Minder, Dan Bilefsky, Mateusz Zuwarik and Niki Kitsantonis of The New York Times.

A Section on 05/27/2014