Ukraine and Russia are seeking a format of returning Ukrainian prisoners staying in Crimea within the framework of diplomatic negotiations under a formula similar to the one used in exchange of political prisoners between the two countries, Ukrainian Justice Minister Pavlo Petrenko has said.

"Now these are closed diplomatic negotiations under a similar formula used in exchange of our political prisoners. We are considering an option for a simple physical transfer of those who expressed desire to serve his sentence in the territory of Ukraine," he told journalists in Kyiv.

The minister also noted the "Savchenko law" should be applied to part of Ukrainian citizens staying in prisons in Crimea and "some of them have to be released ahead of time."

"Now the main issue is what transfer mechanism will be determined with that party," Petrenko stressed.

He admitted that could be "a separate exchange with written commitments that we provide guarantees for their safety and take to the territory of Ukraine." The convention on extradition of convicts to serve their sentences could be also applied, the minister said. But Ukraine does not agree on this option because it considers Crimea to be Ukrainian territory, while the convention provides for transfer of convicted persons from the territory of another state.