Many websites were victims of an alleged hack attack on Sunday, the election day for Russia’s parliamentary elections.

Among the prominent sites that were said to have been affected were those belonging to popular Russian radio station Moscow Echo and election watchdog Golos and also opposition news sites.

Moscow Echo editor-in-chief Alexei Venediktov wrote on Twitter that the attack on the website on election day was clearly an attempt to inhibit publication of information about violations.

Golos said it was the victim of a similar "distributed denial of service" (DDoS) attack.Golos said on Twitter, "Massive cyber attacks are taking place on the sites of Golos and the map showing violations."

The attack was reportedly to censor opposition parties’ exposure of Russian prime minister Vladmir Putin’s United Russia party’s vote-rigging tactics.