Photo by Anton Naumlyuk

Dmitry Dinze told RFE/RL on June 22 that Sentsov had lost almost 15 kilograms since he started the hunger strike on May 14, and was experiencing problems with his heart and kidneys.

Dinze told the AP that when he visited Sentsov on June 22, he was "very weak, very pale," despite receiving vitamins and nutrients intravenously, and has dropped from 97 kilograms to 77 kilograms.

Dinze said Sentsov's condition abruptly deteriorated on the 26th day of his hunger strike, and the administration of the penal colony in the far-northern Yamalo-Nenets region had rushed him to a local hospital.

The 41-year-old Sentsov, a vocal opponent of Russia's 2014 annexation of Crimea, was sentenced in 2015 to 20 years on trumped up charges of plotting terror acts.

A native of Crimea, Sentsov and human rights groups say the charges were politically motivated. On May 14, he began a hunger strike, demanding the release of 64 Ukrainian citizens he considers political prisoners.

Western governments and rights organizations have called for Sentsov to be released, and the Russian human rights group Memorial considers him to be a political prisoner.

Several groups have called on Russian President Vladimir Putin to pardon Sentsov, but Kremlin spokesman Dmitry Peskov told reporters that the Ukrainian film director would have to ask for the pardon himself before it could be considered.

Dinze said on June 22 that Sentsov would not submit a request for a pardon.