Russia election: Vladimir Putin celebrates victory
Vladimir Putin and his supporters are celebrating victory in Russian elections, that will give him a third presidential term after spending the last four years as the country's PM.
With more than 99% of the ballots counted, he secured nearly 64% of the vote, election officials say.
Mr Putin told supporters in Moscow he had won in an open and honest battle.
But Golos, a leading independent election watchdog, said the polls could not be considered fair and open.
It said there were instances of forced voting, numerous reports of "carousel" voting - in which voters cast multiple ballots - and that campaigning had been insufficiently competitive.
"Such elections cannot be called fair, just and open according to the Russian constitution and international standards", a Golos spokeswoman said at a news conference on Monday morning.
The group put Mr Putin's count at just over 50% - far less than the official figure given by the election commission.
Russia will feel divided about this announcement - those who supported Mr Putin will say the opinion polls all indicated he would win with 60% and that there has been more scrutiny and openness in this election than ever before.
But those who voted against him will say look at the violations we think there were in December's parliamentary elections - we feel suspicious that is happening this time too.
Mikhail Prokhorov, a billionaire businessman who did not do very well in the election, has already said he is worried about violations and collecting a dossier. Even the Communist candidate, who has always been a loyal opposition figure, was furious, saying his people have allegations of fraud.
Those claims will have to be investigated, but that does not necessarily mean the challenge will stand. There was an inquiry into allegations of violations in December's elections but it did not stop the election committee saying the official results stood.
Opposition groups have also alleged widespread fraud, and plan a protest rally in Moscow later on Monday.'Believe in Putin'
Tens of thousands of supporters of Mr Putin - with Russian flags and banners - took part in a concert outside the Kremlin to celebrate his victory late on Sunday.
Making a brief appearance with current President Dmitry Medvedev, Mr Putin thanked his supporters from "every corner" of the country.
"I promised you we would win, and we won," he said, his eyes watering. "Glory to Russia!"
"We have won in an open and honest battle.
"We proved that no one can force anything on us."
Slogans on the banner included "Putin - our president" and "We believe in Putin".
Mr Putin, who supported Mr Medvedev in the Kremlin race in 2008 and became prime minister because of a constitutional ban on a third consecutive term as president, will now be in office until 2018. He could then run for another six-year term.
There was tight security around the capital, with 6,000 extra police brought in from outside.'Grandiose scale of falsifications'
On Monday morning the electoral commission said that with more than 99% of the votes counted, Mr Putin won 63.75%, enough to give him a first-round victory over nearest rival Gennady Zyuganov, who polled 17.19%
The other three candidates were in single digits.
The turnout is predicted to be about 63%.
After the polls closed, Mr Zyuganov - the leader of the Communist Party who has previously been relatively loyal to Mr Putin - described the elections as "unfair and unworthy".
But he said that with increasing public anger, Mr Putin "would not be able to rule like he used to".
"These elections cannot be considered legitimate in any way," said Vladimir Ryzhkov, one of the leaders of the street protest movement, which was not represented in the election.
However, Mr Putin's campaign chief Stanislav Govorukhin described the poll as "the cleanest in Russian history".
The election was held against a backdrop of popular discontent, sparked by allegations of widespread fraud during December's parliamentary elections in favour of Mr Putin's United Russia party.
The alleged fraud came despite the presence of thousands of independent observers and web cameras at polling stations.
Opposition blogger and anti-corruption campaigner Alexey Navalny told the BBC: "Grandiose scale of falsifications, especially in Moscow... mass use of carousel voting."
Also on Monday morning, Mr Medvedev announced he had ordered a review of the conviction of jailed former tycoon, Mikhail Khodorkovsky.
Mr Khodorkovsky, a prominent Kremlin critic who was once Russia's richest man, was found guilty of embezzlement in 2010 in what many considered to have been a politically motivated trial.