The European Union has reiterated its call on Moscow to release all Ukrainian citizens “illegally detained” both in Russia and in the occupied Crimea Peninsula.

In a statement on January 10, a spokeswoman for EU foreign policy chief Federica Mogherini cited the cases of Pavlo Hryb, a 20-year-old Ukrainian man charged with abetting terrorism, and Crimean Tatar activist Edem Bekirov, who was detained last month upon entry into Crimea.

The spokeswoman, Maja Kocijancic, said the EU expects both men to be immediately released and granted access to the special medical treatment they need.

Kocijancic also called for the immediate release of the crew of the three Ukrainian vessels captured by Russia in the Black Sea in November.

"International human rights observers must be granted full, free and unhindered access to the Crimean Peninsula," she also said, adding that the European Union "remains committed to fully implementing its policy of non-recognition of the illegal annexation of Crimea."

Russia seized control of Ukraine's Crimea region in March 2014, after sending in troops and staging a referendum dismissed as illegal by at least 100 countries.

Moscow is also backing separatists in a war against Ukrainian government forces that has killed more than 10,300 people in eastern Ukraine since April 2014.