Moscow (CNN) More than 1,000 protesters were detained Saturday by police in the center of Moscow, in a crackdown on opposition supporters demanding free and fair elections.

The local branch of the Ministry of Internal Affairs said at least 1,074 people were detained, while OVD-Info, an independent monitoring group, put the number at 1,127.

Thousands of Russians pledged to attend the protest in the capital Saturday, after Russian authorities banned a number of independent and opposition candidates from taking part in municipal elections in September.

Authorities stated that the candidates were barred from running because they had failed to obtain a sufficient number of signatures to be put on the ballot paper. Opposition politicians and supporters have rejected this allegation.

The decision has sparked a number of protests across Russia this month, including the largest demonstration in recent years last weekend, when 22,000 people took to the streets. Protesters threatened to hold an even larger demonstration Saturday, which was subsequently declared illegal by the authorities.

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