Press secretary of the Ukrainian Foreign Ministry Mariana Betsa says the ministry is considering all possible options for the release of Ukrainian filmmaker, public activist, Oleh Sentsov from Russia's prison.

In particular, when answering journalists question at a briefing on May 21 whether it is possible to swap Sentsov for Chief of RIA Novosti's Kyiv office Kirill Vyshinsky, indicted on charges of high treason in Ukraine, she said that such an option is not excluded, the Novoye Vremya weekly reported.

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"All is possible. I cannot disclose all the details, because if we had announced them in advance, then [Deputy Chairman of the Mejlis of the Crimean Tatar people] Akhtem Chiygoz and [Deputy Chairman of the Mejlis of the Crimean Tatar People] Ilmi Umerov would not have been released yet. I can say only that negotiations are underway," Betsa said.

She stressed that "all Russian citizens who were detained or convicted in Ukraine are criminals, while Ukrainian citizens, illegally arrested or convicted in Russia, are political prisoners."

Russia is blocking all Ukraine's appeals as for providing access to Sentsov. More than 20 such applications have been submitted over the past year, the official said.

It was earlier reported that the Ministry of Foreign Affairs of Ukraine appealed to Russia due to the fact that Sentsov had declared hunger strike on May 14 indefinitely.

He went on hunger strike against the actions of the Kremlin, demanding the release of all the Ukrainian political prisoners held in Russia.