Russia's Justice Ministry has canceled the registration of the political party led by Aleksei Navalny, a vocal critic of President Vladimir Putin.
The Justice Ministry said on April 28 that the Progress Party had not fulfilled a requirement to register operations in at least half of Russia's regions.
Navalny's Party of Progress had agreed to run on a joint platform in the 2016 parliamentary elections with RPR-Parnas, co-founded by slain politician Boris Nemtsov.
"Of course, this is a reaction to the creation of the democratic coalition," Navalny said on his website.
"Party of Progress will stay as a political structure because...the party is not a paper, but people and ideas," Navalny said.
The parties decided to form a coalition after Nemtsov's assassination in February just outside the Kremlin's walls as he walked home with his girlfriend.
Critics of President Vladimir Putin say he bears ultimate political responsibility for the gunning down of Nemtsov.
The Kremlin denies stifling dissent and Putin has ordered law enforcement bodies to investigate the case in full.