Voters across Europe severely rebuked many incumbent governments in elections in 25 countries for seats in the European Parliament, early returns and exit polls showed Sunday evening.

The dominant trend emerging was that people favored opposition candidates for seats in the 732-seat body, a key lawmaking institution of the European Union. Parties that are skeptical of further European integration also did well.

The rebuke was spread out equally among governments that supported the U.S.-led invasion of Iraq and those that opposed the war. In countries whose governments supported the war, such as Britain, political analysts said that public opposition to the invasion was an important factor in defeats of the ruling parties.

The elections, which took place Thursday through Sunday, have no direct effect on sitting national governments. But the results are viewed as a barometer for future domestic elections.

With 350 million eligible voters stretching from Ireland in the west to Hungary in the east, the elections were one of the largest exercises in electoral democracy in the world. But turnout was estimated to average only about 45 percent. It was particularly low in formerly communist countries of Eastern Europe that entered the union in May, where people were voting in a Europe-wide election for the first time.

Many Europeans see the joint parliament, which alternates between chambers in Brussels and Strasbourg, France, as a distant institution that has little effect on their lives.

In Germany, European Parliament candidates from Chancellor Gerhard Schroeder's Social Democratic Party won just 21.6 percent of the vote, according to exit polls, the party's lowest showing in an election since World War II.

In France, President Jacque Chirac's ruling party, the conservative Union for a Popular Movement, was similarly humiliated, winning just 16 percent of the vote.

Chirac and Schroeder led the European opposition to the Iraq war. Analysts said that the vote reflected voter unhappiness with stagnant domestic economies and efforts to scale back generous social welfare systems.

Results from Britain, which voted last week, showed candidates from Prime Minister Tony Blair's Labor Party losing to the opposition Conservatives, which analysts said reflected voter disenchantment with Blair's close embrace of President Bush and the Iraq war. The ruling party in the Netherlands, which also has a small military contingent in Iraq, also suffered big losses.

In Italy, where counting was slow, exit polls showed the coalition of Prime Minister Silvio Berlusconi -- another staunch Bush administration ally on Iraq -- losing ground to opposition groups. Final results were not due until Monday, and Berlusconi made it clear he would not step down if his party was defeated.

In Belgium, the ruling Flemish Liberals, the party of Prime Minister Guy Verhofstadt, another war opponent, were also heading for a resounding defeat.

One ruling party that defied the anti-incumbent mood was in Spain, where the Socialist Workers' Party, elected into office on March 14, won the vote. It had gained widespread support for pulling Spanish troops out of Iraq and promising numerous social policy changes.

Both the Spanish Socialists and the center-right Popular Party were looking to Sunday's European elections as a kind of rematch of the March vote, with the Popular Party seeking to prove that the earlier election was a fluke, coming just three days after bombings aboard commuter trains in Madrid killed 190 people and injured more than 1,800.

The newly elected ruling party in Greece also defied the anti-incumbent trend.

Parties voicing skepticism about European Union integration appeared to make big gains. In the Czech Republic, one of the East European countries voting for the first time for seats in the European Parliament, the Civic Democratic Party, which opposes ceding more power to the EU headquarters in Brussels, was projected to win more seats in the European Parliament than the ruling coalition.

In Britain, early initial returns showed that the U.K. Independence Party, which opposes European integration, more than doubled its share of the vote to above 15 percent.

Unlike in the rest of Europe, turnout in Britain increased over the last European elections because of a new postal balloting system and heightened anti-integration fervor.

In Hungary, the winner appeared to be the Fidesz movement of former prime minister Viktor Orban. Campaigning as a populist, he has questioned whether the government has protected Hungary's interests strongly enough in the EU and has asked for a debate over whether Hungary should keep its troops in Iraq.

Fidesz won 47.4 percent -- the biggest victory ever for a center-right party -- compared to 34.3 percent for the ruling Socialists. Turnout in Hungary was 37 percent. Ruling parties in Poland and Portugal also appeared headed for defeat.

Meanwhile, extremist parties seemed to be scoring well. In France, the anti-immigrant National Front appeared likely to gain seats by winning 10 percent of the vote, nearly doubling its showing from the last European elections in 1999. In Belgium, the Flemish Block, a nationalist party, was expected to win about three seats.

Correspondent Glenn Frankel in London and special correspondents Kriszta Fenyo in Hungary and Robert Scarcia in Barcelona contributed to this report.

Jean-Marie Le Pen, leader of France's anti-immigrant National Front party, and his daughter, Marine, cast ballots for the European Parliament at a polling station west of Paris. Extremist parties appeared to be scoring well in voting for seats in the 25-nation body.