Russia's only independent election watchdog has said it has received over 5,000 complaints of "voter irregularities".

The group also accused the government of carrying out its campaign of intimidation online while more than a hundred anti-government protesters have been arrested by Russian police.

But, preliminary polls show Prime Minister Vladimir Putin's leading United Russia Party's popularity has dropped significantly, gaining less than 50 per cent of the vote as compared to previous years.

Simon McGregor Wood reports.