German Chancellor Angela Merkel has described the surge in support for far right and Eurosceptic parties in the EU elections as “regrettable”, saying the response must be to boost the economy.
The three big centre-right, left and liberal blocs in Europe’s parliament are still on course for a majority.
But they have all lost seats to parties vowing to reduce the power of the EU or abolish it completely.
France’s PM said the far right victory there was a political “earthquake”.
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Mrs Merkel – whose conservative Christian Democratic Union won a comfortable 35% of the vote in Germany – said it was now up to the established parties of Europe to win voters back.
“The best way is to focus on improving competitiveness, on growth and creating jobs. This is the best answer to the disappointed people who voted in a way we didn’t wish for,” she said.
In France, where the far right anti-immigration Front National stormed to victory with a preliminary 25% of the vote, Socialist President Francois Hollande held an urgent meeting with his cabinet on Monday.
There was no official immediate response, but Prime Minister Manual Valls described it as a political “earthquake” and told reporters that Europe needed “another orientation” to tackle the popularist surge.
“There is not a single minute to lose,” he told French media, promising to push through tax cuts. “We need to show courage because France must reform. For too long, left and right together, we have avoided deeply addressing things,” he said.
Alexis Tsipras, leader of Greece’s radical left opposition Syriza, has called for an early election after his party made sweeping gains
UKIP leader Nigel Farage (C) said further European integration was no longer an “inevitability”
Far right leader Marine Le Pen said France could not ignore the voices of her National Front supporters
Hugh Schofield, BBC News, Paris
What has happened with this extraordinary election result is that the Front National has taken a large stride in the direction of responsibility.
Today – unbelievably – it has the largest number of French MEPs. In a legislative body that is an integral part of the European system of government, the FN – the historic pariah – is stronger than both the Gaullists and the Socialists.
What this means is that from now on it will be quite unacceptable for the French establishment to ignore the FN, and to pretend that its ideas do not matter.
For the mainstream parties to treat this victory as they have all other FN advances – as an irritating aberration to be countered with routine shouts of ‘Racist!” – would be an act of monumental stupidity and arrogance.
From ‘untouchables’ to EU force
The anti-EU UK Independence Party (UKIP) is celebrating winning 27% of the vote, marking the first time in a century that a party other than the Conservatives or Labour has won any UK election.
Prime Minister David Cameron, whose Conservative party lost seven seats, said it was clear voters were “deeply disillusioned” with Europe and that the message was “received and understood”.
David Cameron: “People are deeply disillusioned with the European Union”
But he insisted he would neither bring forward the date of an in/out referendum on UK withdrawal from the EU – scheduled for 2017 – nor seek a pact with UKIP.
‘Truly democratic debate’
Despite the unprecedented Eurosceptic gains across the Union, Jose Manuel Barroso, outgoing president of the European Commission, insisted that the pro-EU blocs still had “a very solid and workable majority”.
The centre-right European People’s Party appears set to win 213 out of the 751 seats, with 28.5% across the bloc, according to estimated results issued by the European Parliament. That would make it the biggest group – but with more than 60 seats fewer than before.
The Socialist alliance has a projected 190 seats, with 25%, the Liberals 9% and the Greens 7%.
The Eurosceptic Europe of Freedom and Democracy group appeared to have around 38 seats – including the 24 for UKIP, but the number of non-attached right-wing MEPs is set to rise, boosting the Eurosceptic camp.
But Mr Barroso said a “truly democratic debate” was needed to address the concerns of those who did not vote, or “voted in protest”.
Provisional results put the turnout at EU 43.1%, the first time turnout had not fallen since the previous election, but only an increase of 0.1%.
The BBC’s Jeremy Vine uses graphics to show how EU citizens voted
In other result highlights:
Italy In final results, centre-left PM Matteo Renzi (above) scores strong 40%, fending off ex-comic Beppe Grillo’s anti-establishment Five Star with 21%, and ex-PM Silvio Berlusconi’s Forza Italia with 17%
(Based on exit polls/provisional results)
France National Front take 25% of the vote at 24 seats; Centre-right UMP 21%; President Hollande’s Socialists a poor third with 14% – lowest ever EP score
Britain Eurosceptic UKIP in first place, with 27%, Conservatives on 24% and Labour about 25%. Junior coalition partner Lib Dems lose 10 seats, retaining only one, Greens take 8%.
Germany Angela Merkel wins another election with 35% for her Christian Union. 27% for the centre-left SPD. Eurosceptic AfD score strong 7%. Neo-Nazi National Democratic Party of Germany (NPD) wins its first EU seat
Greece Partial results show far-left Syriza on 26%, PM Antonis Samaras’ New Democracy on 23%. Far-right Golden Dawn set to get three MEPs, with 9%. Syriza leader Alexis Tsipras has asked the Greek president to call early national elections.
Sweden Social Democrats take 24%. Feminist Initiative becomes first feminist party to gain an EU seat.
The election is the biggest exercise in multi-national democracy in the world. The vote will affect the lives of the EU’s 500 million citizens.
The parliament’s powers have expanded since the last election in 2009, and it is hoping to have a decisive say in who gets the EU’s top job, president of the European Commission.
You can follow full coverage with all the latest updates at bbc.co.uk/vote2014.
BBC News – Europe