Natalia Kaplan, sister of Ukrainian filmmaker and Russia's political prisoner Oleh Sentsov, says a doctor visits her brother every day.

"The doctor came to Oleh today. He visits him every day, assessing his condition as stable. It was cold in his prison cell, so the heating was increased," she told Hromadske Radio on May 22.

Read alsoUkraine's foreign ministry: All options considered for release of Sentsov from Russian prison

According to Natalia, representatives of the Russian Prosecutor's Office and the Federal Penitentiary Service visited her brother and dissuaded him from starvation.

"But he stands firm as before," she added.

Kaplan said she did not have grounds for distrusting the doctor, because it is an emergency situation for the colony and they will try to maintain Sentsov's state of health. Now information about the state of his health can be received only from a lawyer as no one else is allowed to the Ukrainian political prisoner. The lawyer is going to visit him next week.

As UNIAN reported earlier, Russia's security forces detained Sentsov together with Oleksandr Kolchenko in occupied Crimea in May 2014 on charges of organizing terrorist attacks on the peninsula.

In August 2015, the North Caucasus District Military Court in Russia's Rostov-on-Don sentenced Sentsov to 20 years in a high-security penal colony. Kolchenko was sentenced to 10 years in prison. Both men pleaded not guilty.

Sentsov 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.