Russia's liberal Yabloko party, which opposes Moscow's invasion of Ukraine, on Friday filed an appeal against a Supreme Court ruling barring it from the parliamentary election in September.
"Yabloko will be on the ballot for the Duma election," party leader Nikolai Rybakov said in a video showing appeal being submitted.
Experts expect, however, that the Kremlin-controlled court will uphold its decision in an appeal hearing scheduled for Monday.
Rybakov said his party's lawyers have conclusively demonstrated that there were no grounds for excluding Yabloko from the September election.
"It was all made up, and we will continue to prove that within the framework of Russian legal provisions," he said.
The Supreme Court ruled on Monday in favour of a lawsuit brought by the nationalist pro-Kremlin Rodina (Motherland) party, barring Yabloko from the parliamentary election.
Judge Vyacheslav Kirillov, who has been criticized as a Kremlin enforcer, sided with the prosecution, which deemed Rodina's complaint against the electoral commission justified.
The central electoral commission unexpectedly voted unanimously in July to approve Yabloko's participation in the Duma election.
Nationwide parliamentary election and local elections are scheduled to take place from September 18 to 20 in Russia.