Vladimir Putin has declared victory in Russia's presidential elections, returning for a third term after spending the last four years as the country's prime minister.
Exit polls and preliminary results gave him about 60% of the vote, meaning he had been elected for a third term as president and had avoided a run-off with his nearest rival, the BBC reports.
Mr Putin told supporters at a rally in central Moscow they had won in an "open and honest" battle.
However, opposition groups have reported widespread fraud, with many people said to have voted more than once and called for mass protests in central Moscow on Monday.
The League of Voters volunteer observer group said it had recorded 3000 violations in total.
Meanwhile tens of thousands of supporters of Mr Putin gathered with Russian flags and banners outside the Kremlin for a concert to celebrate his victory.
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. We have won. Glory to Russia,"
He said the people had clearly rejected attempts to "destroy Russia's statehood and usurp power".
Vladimir Putin was head of state from 2000 to 2008, but was barred by the constitution from standing for a third consecutive term. He faced four challengers, with main rival the Communist Party chief, Gennady Zyuganov, a distant second.
Former Soviet leader Mikhail Gorbachev says he doubts the election is fair, while former prime minister Mikhail Kasyanov believes there will be more demonstrations over the result.