Dutch opposition parties critical of the Iraq war scored significant gains at the start of elections for the European Parliament, while Prime Minister Tony Blair lost support across Britain in local voting, key tests since the invasion last year.

Iraq, as well as domestic issues, concerned voters as the 25 nations of the recently expanded European Union began electing legislators — a four-day process that started Thursday in Britain and the Netherlands.

While Britain's results in the EU vote will not be clear until Sunday, the local vote showed a stinging backlash to Blair, whose popularity has slumped amid lingering doubts about his judgment and truthfulness.

Blair's Labour Party (search) had been expected to suffer losses — the usual fate of governments between national elections. Instead, the focus was on the size of the loss, which appeared to be significant with results from 83 of the 166 local councils declared.

Blair and his ministers acknowledged that the deeply divisive war cast a shadow over campaigning in Britain for local council elections as well as for EU lawmakers.

"There is clearly a strong protest vote, and we have to take account of what people are telling us," Culture Secretary Tessa Jowell said as results came in early Friday. "Iraq is certainly a factor."

Labour was down 211 seats; the main opposition Conservative Party (search) had gained 103 seats; and Britain's third largest party, the Liberal Democrats (search) — which staked its campaign heavily on it being the only major party to oppose the war — gained 67 seats.

The British Broadcasting Corp. projected that Labour would trail in third place with 26 percent of the total vote, behind the Conservatives with 38 percent and the Liberal Democrats with 30 percent.

"Iraq and the worries over Iraq have been a shadow over our support but in the end you have to take decisions that are right and you have to see them through," Blair told reporters Thursday at the G8 summit on Sea Island, Ga. before polls in Britain closed.

Ireland and the Czech Republic voted for the European Parliament on Friday but most of the 25 EU nations are waiting until Sunday.

In the Northern Ireland town of Londonderry (search), Catholic teenagers and children pelted police with petrol bombs, paint-filled balloons, bricks and rocks as the officers guarded ballot boxes following European Parliament elections.

Londonderry's mayor said violence outside stations in four hard-line Catholic parts of the city had become a ritual. Similar attacks have been mounted on police and polling staff in the same locations following nearly every election here since the 1980s.

Police said several vehicles were damaged in the latest violence. One electoral official suffered minor cuts when a window inside a polling station was shattered.

In the Netherlands, unofficial results with most of the EU parliament vote counted showed strong gains for leftist opposition parties and losses for the conservative parties in the Dutch coalition government.

Taking advantage of anti-war sentiment among the Dutch people, the opposition made Iraq a campaign issue as the government weighs whether to extend the mandate of nearly 1,400 Dutch troops in Iraq beyond July 15.

Also, the new Transparent Europe (search) party of whistle-blower Paul van Buitenen (search) won two of the 27 Dutch EU seats. Van Buitenen's claims of mismanagement in Brussels in 1998 led to the resignation of the entire European Commission.

European final results are to be announced on Sunday.

Some 14,670 candidates were running for 732 seats in the European elections, held every five years. The 10 new member states from Eastern Europe were electing their first representatives in the parliament.

Britons voted in three polls, selecting representatives for the European Parliament; local councils across England and Wales; and for a London mayor.

The main opposition Conservative Party, which supported the war, had hoped to benefit from voter dissatisfaction on issues such as education, crime, immigration and transport.

In the European elections, the Conservatives campaigned against a new constitution, but feared that some traditional supporters might defect to the upstart U.K. Independence Party (search), which wants Britain to get out of the European Union.

Celebrity candidates in the European campaign included Portugal's 1998 Nobel literature laureate, Jose Saramago, on the Communist Party's ticket; Mladen Rudonja, the Slovenian soccer hero whose goal got the national team into the 2002 World Cup; Slovakian former National Hockey League forward Peter Stastny; Estonian supermodel Carmen Kass, and Czech porn star Nora Baumberger (screen name Dolly Buster).

When the EU expanded May 1, taking in 10 new members, its population increased to 450 million. Eastern European nationalist parties that campaigned against giving up powers to join the EU are taking their message into the bloc with campaigns for seats in the assembly.

Although no single issue has dominated the campaign EU-wide, efforts to negotiate a constitution for the union have been a major issue for those parties that see the charter as a threat to national sovereignty.

Malta and Latvia vote on Saturday, when Italy begins two days of voting. On Sunday, ballots will be cast in Austria, Belgium, Cyprus, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Lithuania, Luxembourg, Poland, Portugal, Slovenia, Slovakia, Spain and Sweden.