The leader of Russia's only independent election monitor was detained at a Moscow airport for 12 hours, a colleague said Saturday — the latest government pressure on a watchdog that has documented thousands of election law violations ahead of Sunday's parliamentary vote.

Golos has compiled some 5,300 complaints from voters during the latest campaign — most linked to United Russia, the party that dominates the Kremlin and supports Russian Prime Minister Vladimir Putin. Roughly a third of the complainants — mostly government employees and students — say employers and professors are pressuring them to vote for the party.

Golos leader Lilya Shibanova was held at Moscow's Sheremetyevo airport after refusing to give her laptop to security officers late Friday, the group's deputy director Grigory Melkonyants said. She was released after giving up the computer, he said.

"The detention was politically motivated," Melkonyants told The Associated Press.

The detention follows a decision Friday by a Moscow district court to fine Golos $1,000 for violating a law forbidding the publication of public opinion research within five days of an election.

The group has come under growing pressure since Sunday, when Putin accused Western governments of trying to influence the election through their funding of unidentified Russian non-governmental organizations. Golos, whose name means "vote," is supported by grants from the United States and Europe.

The group's staffers all over Russia "face threats and psychological pressure," Melkonyants said.

Kremlin-controlled NTV television showed a half-hour program on Friday evening that attacked Golos directly. The program included shots of suitcases full of U.S. dollars and claimed that Golos was openly supporting opposition parties and trying to discredit the elections.

Kremlin-approved parties

United Russia dominates Russia's political life and has received overwhelmingly favourable coverage during the campaign, mostly from Kremlin-controlled national television. But the party is increasingly disliked, seen as representing a corrupt bureaucracy and often called "the party of crooks and thieves."

Only seven Kremlin-approved parties have been allowed to field candidates for parliament this year, while the most vocal opposition groups have been denied registration and barred from campaigning.

The Kremlin is determined to see United Russia maintain its majority in parliament. President Dmitry Medvedev and Putin both made final appeals for the party on Friday, warning that a parliament made up of diverse political camps would be incapable of making decisions.

Putin needs the party to do well in the parliamentary election to pave the way for his return to the presidency in a vote now three months away.

Independent pollster Levada Centre said last week that United Russia will receive 53 per cent of the vote, down from the 64 per cent it got in the 2007 vote. This would deprive the pro-Kremlin behemoth of the two-thirds majority that has allowed it to amend the constitution.

Another poll by Levada released in late November shows that 51 per cent of Russians believe the election only "imitates competition."

The Helsinki Commission, a federal board that advises on U.S. policy about security, human rights and other issues involving Europe, criticized the court ruling to fine Golos in a statement released late Friday.

"The campaign against Golos provides additional reason for doubt about the legitimacy of the parliamentary election that will take place in Russia on Sunday and the broader state of democracy there," it said.