Lutkovska said that she has no access to Ukrainian prisoners who are illegally held in custody in Russian prisons.

"Unfortunately, there is no such possibility today. In theory, I could go to Russia but unfortunately I’m unable to exercise my functions there as an ombudsman," Lutkovska told a Kyiv press conference on Friday.

She recalled that a few weeks ago, she had sent a letter to the Russian Commissioner for Human Rights telling her there are Russian citizens kept in penitentiary facilities across Ukraine.

Read alsoUkraine MFA warns Ukrainians of dangers of traveling to Russia"I am inviting her to come and visit these Russian citizens and, in response, I am asking her to give me an opportunity to visit those Ukrainians who are held in custody in Russia. I'm waiting for the answer from my counterpart, I hope that I will see one," Lutkovska said.

Read alsoKyiv lays responsibility for life of detained 19-year-old Ukrainian on RussiaAs UNIAN reported earlier, Russia's Human Rights Ombudswoman Tatyana Moskalkova does not believe in the existence of the Russian FSB “secret prison”.