Dec. 3 (Bloomberg) -- Vladimir Putin's party swept a parliamentary election that European observers said was ``not fair,'' giving the president the mandate he sought to keep guiding Russia after he leaves office next year.

The Central Election Commission said United Russia took 64.1 percent and two other pro-Kremlin parties a combined 16 percent of yesterday's vote with 98 percent counted, handing them more than four-fifths of the seats in the State Duma. Turnout was 63 percent, up more than 7 percent from 2003. Opposition parties complained of unprecedented vote-rigging.

The elections were ``not fair and failed to meet many OSCE and Council of Europe commitments and standards for democratic elections,'' the observers from bodies including the Organization for Security and Cooperation in Europe said in a statement issued in Moscow today.

Putin, 55, who cannot run in the March 2 presidential election because of a ban on three consecutive terms, had called for Russians to vote in large numbers for his party, saying this would give him the ``moral right'' to retain a leading role. He has yet to reveal what that will be.

The vote ``took place in an atmosphere which seriously limited political competition and with frequent abuse of administrative resources, media coverage strongly in favor of the ruling party and an election code whose cumulative effect hindered political pluralism,'' the observers' report said. ``There was not a level political playing field in Russia in 2007.''

`Abuse of Power'

The 70-strong observer mission was particularly critical of Putin throwing his weight, and the apparatus of the state, behind United Russia. ``The merging of the state and a political party is an abuse of power and a clear violation of international commitments and standards,'' the statement said.

It also noted ``persistent reports of harassment of opposition candidates, detentions, confiscation of election material, threats against voters and allegations of the potential misuse'' of absentee ballots.

Opposition parties also alleged that the state used its resources to rig the result in favor of United Russia. Communist leader Gennady Zyuganov denounced unparalleled ``administrative pressure,'' describing the elections as ``not democratic, not fair and not free.'' His party plans to contest the results in the Supreme Court. The U.S. called on the Russian authorities yesterday to investigate reports of election-day irregularities.

`No Such Violations'

Vladimir Churov, the head of Russia's Central Election Commission, dismissed all allegations of irregularities. ``There were no such violations, and there could not have been,'' he said in remarks broadcast on state television.

An observer mission from the Commonwealth of Independent States, a loose group of former Soviet republics, found the vote ``democratic, free and transparent,'' Russian news agency RIA Novosti reported.

``The Kremlin got what it sought: a big turnout and a landslide victory for United Russia,'' Masha Lipman, an analyst at the Carnegie Endowment for International Peace's Moscow Center, said in an interview. Putin said that if his party won a convincing majority, ``he will have the moral right to hold everyone to account,'' she said.

Economic Boom

Investors welcomed the prospect of a continuation of the president's policies. Russia's economy has expanded nearly 7 percent a year since Putin was first elected in 2000, fueled by high energy prices, and the value of Russian stocks has grown by $1 trillion.

Russian stocks fell in line with other European markets. The ruble-denominated Micex Index sank 0.2 percent to 1,846.85 at 13:24 p.m. in Moscow.

With the vote count nearly complete, the Communist Party was in second place with 11.6 percent. Two other parties that support Putin also cleared the 7 percent barrier required to enter the lower house of parliament. Vladimir Zhirinovsky's Liberal Democratic Party of Russia had 8.2 percent and Fair Russia, led by Sergei Mironov, speaker of the upper house of parliament, had 7.8 percent. Eleven parties contested the election.

Several regions reported overwhelming support for Putin's party. In the largely Muslim southern republic of Chechnya, which tried to secede in the mid-1990s, United Russia had 99.3 percent with about 60 percent of the votes counted. Neighboring Ingushetia delivered 98.7 percent for the party.

Moscow Results

In Moscow, where parties opposed to Russia's increasingly authoritarian system had traditionally fared well, Putin's party had 54 percent with nearly 99 percent of the vote counted. Official results will be published at the end of this week.

``Putin will consider this result a victory,'' Olga Kryshtanovskaya, a political analyst at the Russian Academy of Sciences in Moscow, said in a telephone interview. ``I am sure he will manage to maintain his power.''

United Russia and its allies would have almost 400 of the 450 Duma seats, based on the nearly complete results, with the Communists holding the remainder.

The Russian leader, who headed United Russia's list of candidates for the Duma, hasn't endorsed any nominee to replace him as president. Pollsters say that any politician who gets Putin's blessing will win.

Analysts say that among potential successors to Putin are First Deputy Prime Ministers Sergei Ivanov, 54, and Dmitry Medvedev, 41, along with Prime Minister Viktor Zubkov, 66. Candidates must come forward by Dec. 23.

To contact the reporters on this story: Sebastian Alison in Moscow at salison1@bloomberg.net; Henry Meyer in Moscow at Hmeyer4@bloomberg.net.

Last Updated: December 3, 2007 05:44 EST