Preliminary results showed United Russia with commanding leads in each of the 12 local legislative elections in a vote that the losing Communist Party said was riddled with fraud.

Election monitors from Russia's Golos association also said the vote had been rigged.

United Russia rides the coattails of its chairman and Russia's former president Vladimir Putin and already includes the vast majority of the country's political elite.

The party's leader in parliament where it can pass Kremlin legislations without anyone else's support said the results showed that United Russia's dominance in Russia was here to stay.

"This tells us that the country's political system works in the voters' favour and that they they trust it," Boris Gryzlov said in statement posted on the party's website.

"I would like to thank all the voters.

This is both an evaluation of the party, a sign of support for the authorities, support of the president and support for our party leader Putin," he added in televised remarks.

United Russia was further boosted by figures showing turnout of about 50 percent higher than previous local elections.

The results flew in the face of polls indicating lower levels of support for a party that in November was personally condemned by President Dmitry Medvedev for "showing symptoms of stagnation".

The state-controlled media has recently highlighted a series of corruption scandals involving United Russia officials. Surveys had suggested that voters' resentment was also growing because of rising food prices.

Communist Party boss Gennady Zyuganov called the polls the most fraud-riddled in Russia's post-Soviet era.

"We witnessed United Russia using all the dirty tricks invented in the past 15-20 years," Interfax quoted Zyuganov as saying. "This ugliness did not exist before."

The Communist Party had its best showing in central Russia's Nizhny Novgorod region where it looked to be placed second with about 29 percent of the vote.

Zyuganov's claims of fraud were confirmed by activists from Russia's Golos association, an independent election monitoring organisation.