The European Union has called for the immediate release of all Ukrainian citizens illegally detained in Russia and the annexed Crimea.

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"On 14 May 2018, Oleh Sentsov, a film director deported to eastern Siberia, began a hunger strike after four years of imprisonment. Another illegally-detained Ukrainian citizen, Volodymyr Balukh, has also recently spent two months on hunger strike. They have opposed the illegal annexation of the Crimean peninsula and were sentenced, by courts whose jurisdiction the EU does not recognize, in breach of international law and elementary standards of justice," the press service of the EU Delegation to Ukraine said in a statement on May 25.

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Furthermore, the number of Crimean Tatars being persecuted in the annexed Crimea gives rise to great concern.

"Adding to the extremely worrying number of Crimean Tatars who have been persecuted and had their rights gravely violated, activists Server Mustafayev and Edem Smailov were also detained on May 21, 2018," reads the statement.

"The European Union expects international human rights standards on the peninsula to be upheld and all illegally detained Ukrainian citizens in Russia and on the Crimean peninsula to be released without delay," it says.