Finland violated international law when it barred Russian parliamentary speaker Sergey Naryshkin from attending a regional security summit next week in Helsinki, a top Russian official said Tuesday. Naryshkin announced the entire Russian delegation will boycott the proceedings.

Finland blocked Naryshkin’s entry into the country for a meeting of the Organization for Security and Co-operation in Europe’s Parliamentary Assembly because of his inclusion in European Union sanctions against Russia and some of its top officials, Finnish Foreign Ministry spokesman Vesa Hakkinen told Russian-owned Tass. The OSCE is a multinational organization tasked with conflict prevention and the mitigation of potential diplomatic crises through dialogue between European nations. 

“This is a gross violation of Finland’s obligation under international law,” a source within Russia’s Foreign Ministry told Tass. “The country should ensure that an individual has the right to enter Finland to participate in international events even if the individual is on sanctions lists.”

Finland coordinated with officials from European Union member nations and the OSCE before making its decision, Hakkinen added. Naryshkin was one of several Russian government officials targeted with asset freezes and travel bans last year after Moscow’s annexation of Crimea. A prominent Russian politician and ally of Russian President Vladimir Putin, Naryshkin received penalties from both the European Union and the United States. He is a member of Russia's National Security Council.

“The Russian delegation in full will not participate in the session,” Naryshkin said in a statement. “This is the expression of our protest against arbitrariness, against violation of principles of democracy and parliamentarism.” Russian officials will attend the next OSCE assembly in Mongolia, he added.

The OSCE's parliamentary assembly holds periodic summits, during which participating nations can propose diplomatic resolutions. OSCE officials have played in active role in monitoring the eastern Ukraine conflict. More than 6,400 people have died in clashes between Ukrainian government forces and pro-Russian separatist rebels.

The European Union announced its intention last month to extend economic sanctions against Russia until at least January 2016, with penalties to remain in place until the Kremlin demonstrates its commitment to the Ukraine peace process. Russia has denied any military involvement in the conflict and said any Russian nationals active in Ukraine are volunteers.”