* Putin wins presidency - exit polls
* Opposition alleges fraud, plans protests
* Putin faces biggest protests of his 12-year rule
By Timothy Heritage and Guy Faulconbridge
MOSCOW, March 4 (Reuters) - Vladimir Putin triumphed in Russia's presidential election on Sunday and, tears rolling down his cheeks, called his victory a turning point that had prevented the country falling into the hands of enemies.
Putin's opponents complained of widespread fraud, refused to recognise the results and said they would press ahead on Monday with the biggest protests since he rose to power 12 years ago.
But the former KGB spy said he had won a "clean" victory and was on course to return to the Kremlin after four years as prime minister with almost 65 percent of votes, partial results showed.
"I promised you we would win. We have won. Glory to Russia," Putin, dressed in an anorak and flanked by outgoing President Dmitry Medvedev, told tens of thousands of flag-waving supporters at a late-evening victory rally under the red walls of the Kremlin.
Denouncing attempts to "destroy Russia's statehood and usurp power", he said: "The Russian people have shown today that such scenarios will not succeed in our land ... They shall not pass!"
The crowd at one point chanted: "Putin! Putin! Putin!" Some danced to keep warm and drank vodka from plastic glasses, with empty bottles crunching underfoot.
It was a defiant and angry speech which left Putin, 59, on collision course with the mainly middle-class protesters in Moscow and other big cities who have staged huge rallies since a disputed parliamentary poll on Dec. 4.
Two exit polls showed Putin with 58-59 percent of the votes and incomplete results showed him winning more than 64 percent.
His nearest rival, Communist Party leader Gennady Zyuganov, had about 17 percent of votes, and nationalist Vladimir Zhirinovsky, former parliamentary speaker Sergei Mironov and billionaire Mikhail Prokhorov were all below 10 percent, although Prokhorov won plaudits for his campaign.
Zyuganov said his party would not recognise the result and called the election "illegitimate, dishonest and untransparent". Liberal leader Vladimir Ryzhkov also said it was not legitimate.
The protest organisers, who see Putin as an autocratic leader whose return to power will stymie hope of economic and political reforms, said their demonstrations would now grow.
"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," said journalist Sergei Parkhomenko, one of the leaders of the opposition protest movement.
"He is forcing things to breaking point. He is declaring war on us. As a result the base of aversion to him is growing."
Despite the opposition, mainly among well-educated and relatively well-off young professionals, Putin's support remains strong in the provinces and his victory had not been in doubt.
He showed his gratitude in late-night video links with supporters around Russia, including workers at a tank factory in the Urals town of Nizhny Tagil who have denounced the protests.
"You put in their places those people who went one step too far and insulted the working man," Putin told them. "You showed who the Russian people are, the Russian working man, the worker and the engineer. You showed that you are a head higher than any layabout, any old windbag. This was for me the biggest present."
A spokesman later said Putin had wept real tears at the victory rally but said they were caused by the biting wind.
The main challenge for the man credited by many Russians with rebuilding the country's image and overseeing an economic boom in his first presidency, was to win outright on Sunday, avoiding a runoff election by receiving more than 50 percent.
His clear victory will enable him to portray his return to the post he held from 2000 until 2008 as strong public backing against the protesters, whom he has portrayed as a destabilising minority and pawns of foreign governments.
But the reaction to his rallying cry at the victory rally was more muted than expected. Hundreds of buses had brought the crowd to Moscow, signalling that it was a well-organised show of force rather than a spontaneous display of support.
The mood has shifted in the country of 143 million and many people are uncertain whether he will be conciliatory and reformist, or stand in the way of political and economic change.
Putin, who will be inaugurated in May, is likely to revert to the fighting talk against the West that was the trademark of his first presidency and his election campaign.
Economists say a key test of Putin's return will be how far he is ready to go to reform an economy heavily dependent on energy exports, and caution that his populist campaign spending promises could return to haunt him.
"It's a watershed - Russia faces decline and stagnation unless they really kick-start reforms, and push forward an ambitious reform agenda," said Tim Ash, head of emerging markets research at Royal Bank of Scotland in London.
Putin has remained Russia's dominant leader and its most popular politician since stepping aside in 2008 to make way for his ally, Medvedev, because he was barred from a third straight term by the constitution.
Some voters said Putin, who has portrayed himself as a man of action and guardian of stability, was the tough national leader the world's biggest country and energy producer needed.
"I voted for Putin because he was a good president (from 2000-08) and our children were looked after and that's all. That's how I feel," said Maria Fedotova, a 92-year-old grandmother in fur coat and hat, flanked by relatives.
But others are tired of his macho antics, such as horse riding bare-chested, and a system that concentrates power in his hands. They fear he could win another term in six years and rule until 2024 - almost as long as Soviet dictator Josef Stalin.
"They are stealing our votes," said Valentin Gorshun, a patient in Moscow hospital number 19, where more than 90 percent of votes went to United Russia party in December.
"It is probably the same at all hospitals," he said. "I think they are preparing a huge falsification. Emperor Putin has decided everything."
Thousands of opposition activists as well as an international observer mission also monitored the polls.
Vote monitors from the opposition and bloggers posted allegations of election rigging across the country of 143 million. Golos, an independent monitoring group, said it had registered at least 3,500 reports of violations nationwide.
The partial results showed Putin won almost 100 percent of votes in the Chechnya region, with almost 100 percent turnout.
An Interior Ministry spokesman denied there had been any major violations. Election officials also dismissed reports of widespread fraud in the Dec. 4 parliamentary vote that sparked the protests.