Russian Prime Minister Vladimir Putin accused the U.S. authorities Thursday of sponsoring the opposition protesters in Russia after the State Duma election held on Sunday.

Russia's Prime Minister Vladimir Putin visits the Central Elections Commission office in Moscow, on December 7, 2011, to appeal for his registration as presidential candidate in Russia. The presidential voting in Russia is scheduled on March 4, 2012. [Xinhua/AFP]

"I noticed the first reaction of our U.S. colleagues. The U.S. Secretary of State was quick to evaluate the elections, saying that they are unfair and unfree, even before she received materials from the Office for Democratic Institutions and Human Rights observers," Putin said during a meeting with representatives of his All-Russia People's Front movement in Moscow.

U.S. Secretary of State Hillary Clinton on Tuesday said the Russian parliamentary elections were "neither free nor fair". Some other Washington officials also said Washington was seriously concerned by the Russian election.

Putin said Clinton's comments became a "signal" for Russian activists who have begun "active work with the support of the U.S. Department of State."

Massive opposition protests against the alleged vote fraud in favor of Untied Russia took place in Moscow and St. Petersburg following Sunday's elections. Police have arrested over 100 protesters.

Putin said Russia should thwart foreign governments' attempts to interfere in its domestic affairs.

"When money from abroad is invested in political activities inside another country, this concerns us," he was quoted by RIA Novosti news agency as saying.

Punishment for those cooperating with foreign governments should be toughened, Putin added.

Moscow authorities have authorized a demonstration scheduled on the upcoming Saturday but only allowed 300 people to take part.