The Federal Registration Service said the application did not satisfy technical requirements.
Kasyanov's Russian Popular Democratic Union argues the decision is politically motivated.
Kasyanov served as prime minister from 2000 to 2004 during the first term of Vladimir Putin. He has since become a public critic of the president.
(AFP, Reuters)
RFE/RL In Russian
RFE/RL In Russian
UPDATED CONSTANTLY: Visit RFE/RL's Russian-language website, featuring news, analysis, features, streaming audio, and more, in Russian, from RFE/RL's Russian Service.
