MOSCOW — European election monitors said today that Russia's parliamentary ballot was unfair, hours after President Vladimir Putin's party swept 70 percent of the seats in the new legislature.

The victory paves the way for Putin to remain Russia's de facto leader even after he leaves office next spring. Today, Putin described the weekend's election as a vote of confidence in him.

"I headed the United Russia ticket, and, of course, it's a sign of public trust," Putin said in televised remarks.

Sunday's vote followed a tense Kremlin campaign that relied on a combination of persuasion and intimidation to ensure victory for the United Russia party and for Putin, who has used a flood of oil revenues to move his country into a more assertive position on the global stage.

Opposition leader Garry Kasparov denounced the legitimacy of the vote.

"There are no illusions that what is being called elections was the most unfair and dirtiest in the whole history of modern Russia," the former chess champion said at a news conference.

Kasparov, who heads the Other Russia coalition of opposition groups, was arrested and jailed for five days for leading a protest rally in Moscow on Nov. 24. His group wasn't allowed to run for parliament.

Luc van den Brande, who headed the delegation from the Parliamentary Assembly of the Council of Europe, said that officials had brought the "overwhelming influence of the president's office and the president" to bear on the campaign, and that "administrative resources" had been used to influence the outcome.

Goran Lennmarker, president of the Organization for Security and Cooperation in Europe's parliamentary assembly, said it was "not a fair election."

The Kremlin and its allies hailed the vote as an overwhelming endorsement of Putin and his policies.

The Bush administration called for an inquiry into voting irregularities. Communist Party leader Gennady Zyuganov called the election "the most irresponsible and dirty" in the post-Soviet era and party officials vowed to challenge the results.

Kimmo Kiljunen, vice president of the Office of Security and Cooperation in Europe's Parliamentary Assembly, called the elections "strange" and "problematic" because of reports of harassment of parties and confiscation of election materials.

With ballots from nearly 98 percent of precincts counted, United Russia was leading with 64.1 percent, while the Communists trailed with 11.6 percent, the Central Election Commission said.

Turnout was about 63 percent, up from 56 percent in the last parliamentary elections four years ago.

United Russia's victory would give it 315 seats, or 70 percent of the seats in Russia's 450-seat State Duma, the Central Election Commission said. The Communists would have just over 50 seats.