The Election Commission has announced its refusal to register Mikhail Kasyanov, an ardent critic of Russian President Vladimir Putin, EuroNews.net reported Sunday.

The commission reportedly found that more than 13 percent of the required signatures of support submitted by Kasyanov were invalid.

Kasyanov accuses the Kremlin of trying to sabotage his campaign, and pave the way to an easier victory for Dmitry Medvedev.

Other official candidates include ultra-nationalist Vladimir Jirinovski, communist Genadi Zuganov and another pro-Kremlin candidate, Andrei Bogdanov.