Russians are voting in a poll that is being seen as a measure of Prime Minister Vladimir Putin’s popularity, ahead of a planned return to the presidency next year.
Current President Dmitry Medvedev has already confirmed he will be standing down.
Four hundred and fifty members will be elected to the lower house of parliament on Sunday. Seven political parties are fielding candidates in an election taking place across nine different time zones.
International monitoring group Golos is claiming there have been electoral violations and has recorded over 5,000 complaints.
The organisation’s leader Liliya Shibanova was detained at a Moscow airport for 12 hours on Saturday, and allegedly had her laptop confiscated and its contents copied. However, customs officials deny targetting Golos.
Putin has accused the foreign-funded group of meddling in the election process.
The group’s website is seemingly blocked and they are complaining of being hit by cyber-attacks.
Other websites reporting electoral violations have also alledgedly been attacked by hackers.
Meanwhile, according to reports on state television, 12 members of the unregistered Left Front opposition group have been arrested after a demonstration in central Moscow.
The Left Front are denying the legitimacy of Sunday’s ballot.