A citizen of Ukraine who is in custody in the Russian Federation, Oleksandr Kolchenko, has declared a hunger strike demanding the release of another political prisoner, film director Oleh Sentsov, who is also in Russia's jail, the Media zone outlet has said in reference to his lawyer.

His has declared hunger strike since May 31. He doesn't have other requirements, except for the release of Sentsov, Kolchenko's lawyer Andrey Lepehin told the media.

As reported, the Northern Caucasus District Military Court in Rostov-on-Don sentenced Sentsov, who was detained in Crimea in 2014, to 20 years in a high-security penal colony in August 2015 for an attempt to create a so-called terrorist group in Crimea.

He is serving his sentence in a high-security correctional facility known as Bely Medved (White Bear).

On May 16, 2018, Sentsov went on a hunger strike, demanding the release of all Ukrainians held in Russia and occupied Crimea.

Ukraine, the international community has repeatedly called on the Russian Federation to release the illegally convicted Sentsov.