"We have compared speeches and promises Dmitry Medvedev made in his capacity of First Deputy Prime Minister and his pronouncements at the February 27 meeting with voters. They proved identical," Gazeta.ru quoted Yelena Panfilova, Director of Center Transparency International-Russia, as saying.
"This means the presidential candidate engaged in hidden campaigning and enjoyed free airtime," Panfilova told the online edition.
Europe's main election watchdog, the OSCE, and its parliamentary assembly earlier pulled out from their plans to monitor the March 2 election, citing major restrictions. Russia denied the allegations, accusing the organization of bias.
Panfilova said that other officials also campaigned for Medvedev, President Vladimir Putin's longtime ally and preferred successor, by indirectly calling on voters to support the "continuity" of Putin's policies.
Moscow Mayor Yury Luzhkov made appeals on posters and in letters to Muscovites to vote for "preserving stability in the country," which was tantamount to campaigning for Medvedev, Panfilova said.
An expert with rights group Golos cited by Gazeta.ru said Medvedev and Putin, who has agreed to be premier if his ally wins the polls, have dominated television programs during the election campaign.
Other candidates in the elections include Communist leader Gennady Zyuganov, ultranationalist politician Vladimir Zhirinovsky and Vladimir Bogdanov, leader of the tiny pro-Western Democratic Party. A number of other candidates, including former premier Mikhail Kasyanov, were denied registration by Russian electoral authorities, citing 'irregularities' with their applications.
Medvedev, backed by the popular Putin, who has presided over brisk economic growth in recent years, is expected to win the vote easily. Opinion polls showed Medvedev enjoys about 70% of voter support.
Political analysts have also said that authorities have often resorted to unscrupulous methods to ensure sufficient turnout.
Some maternity homes outside Moscow had announcements on their doors that they would not receive pregnant women unless they had obtained absentee ballots, they told Gazeta.ru.
Putin made his final appeal to Russians on Friday, the final day for campaigning before the vote on Sunday, urging them to participate in the polls
"Russia's movement forward must not stop, changes for the better must be carried on," he said. "I am asking you to vote for our common future, for Russia's future on Sunday."
