Vladimir Putin claimed a resounding victory in Russia's election Sunday night, returning to the presidency for a new, six-year term in a vote that opponents condemned as rigged.

The landslide win of 64 percent for the current prime minister came amid widespread allegations of fraud, suggesting that Putin faces a difficult time in the office he held from 2000 to 2008.

I promised you we would win. We have won. Glory to Russia, Putin told thousands of supporters in a tearful late-night address on downtown Moscow's Manezh Square, near the Kremlin. We won in an open and fair struggle.

Denouncing supposed attempts to destroy Russia's statehood and usurp power, Putin declared: The Russian people have shown today that such scenarios will not succeed in our land. ... They shall not pass!

Putin will take the presidential oath of office in May, replacing the man who had succeeded him, Dmitry Medvedev.

With 100 percent of ballots counted, according to news agency RIA Novosti, Putin's 64 percent was followed by Communist Party leader Gennady Zyuganov's second-place 17 percent. In third was Mikhail Prokhorov, billionaire owner of the NBA's New Jersey Nets, at 8 percent. Two other candidates, longtime nationalist politician Vladimir Zhirinovsky and A Just Russia party's Sergei Mironov, finished third and fourth with 6 percent and 4 percent, respectively.

Zyuganov said his party wouldn't recognize the results, calling the election illegitimate, dishonest and untransparent.

Putin's campaign chief, Stanislav Govorukhin, dismissed fraud allegations.

This is the cleanest election in Russia's entire history, Govorukhin said at the headquarters of Putin's United Russia party. The violations our rivals and the opponents of our president will now speak of are laughable.

These elections cannot be considered legitimate in any way, Vladimir Ryzhkov, a leaders of the street protest movement, which wasn't represented in the election, told the BBC.

Opposition groups said they would resume their protests Monday.

The social base of the protest is going to grow and Putin with his team did everything wrong to make this happen. He really helped us, journalist Sergei Parkhomenko was quoted by Reuters as saying. He is forcing things to breaking point. He is declaring war on us. As a result the base of aversion to him is growing.

Independent elections watchdog Golos, or Voice. said it was receiving reports of carousel voting, in which busloads of voters are driven around to cast ballots at multiple sites, CBS News reported. On its election-monitoring website, Golos said it had received over 4,000 complaints.

There have been many people voting more than once, driven around in buses in large numbers in Moscow, said Golos head Lilia Shibanova, adding that similar reports had been received from Novosibirsk, Russia's third-largest city, and the city of Barnaul in southern Siberia.

We, of course, expected carousels, but not on this scale, Alexei Navalny, a popular blogger who is one of the opposition's most charismatic leaders, wrote on Twitter. He noted  [a] grandiose scale of falsifications, especially in Moscow, according to the BBC. 

The alleged fraud came despite the presence of thousands of independent observers and specially installed Web cameras at most of Russia's 90,000 polling stations.

Putin, wearing a long black coat, voted at the Academy of Sciences in Moscow, accompanied by his wife, Lyudmila.

The prime minister left just minutes before three activists from the Ukrainian women's group Femen ran topless into the polling station and tried to steal the ballot box, the Moscow Times reported. They were dragged away by security as they screamed Putin is a thief! One had Stealing for Putin painted across her bare chest.

Police presence in Russia's capital was heavy, with hundreds of police trucks parked in downtown Moscow.