Russian Prime Minister and presidential candidate Vladimir Putin urged the opposition Wednesday to refrain from using "dirty devices" during the upcoming election.

"We know that some are preparing to use schemes to confirm election fraud. They will stuff ballots themselves, monitor this themselves and then present this accusation themselves. We see it and know already," Putin said at a meeting with his election agents and representatives of the All-Russia People's Front.

He urged everyone in the elections to act "within the legal framework and by legitimate means".

He said street protests were expected no matter what the election results were, but opposition members should respect the majority's opinion.

"People who are talking about the need to develop and strengthen democracy should stick to these rules themselves. The main rule is that the opinion of a minority should be respected, but the majority's choice must be obeyed," Putin was quoted by Itar-Tass news agency as saying.

Five candidates are contesting the presidential election, due on Sunday. Putin is widely expected to win his third term in the Kremlin.