Ukraine has called on Friday May 10th for the "urgent" release of its sailors that Russia is holding, since their naval vessels were captured off Crimea last November.
The diplomatic incident has heightened tensions between the neighbours who have been locked in conflict for the last five years, according to AFP.
Ukraine's deputy foreign minister Olena Zerkal, addressing the International Tribunal for the Law of the Sea in the German city of Hamburg, called for the immediate release of the 24 sailors being held in Moscow.
Russia has accused the Ukrainian sailors of violating its maritime borders.
Last November, Russia opened fire upon, then captured the sailors manning three Ukrainian vessels off Crimea, which were trying to pass through the Kerch Strait from the Black Sea to the Sea of Azov.
Zerkal described the sailors' continued detention as "just an additional illustration of Russia's continued disrespect for international law."
"From the moment of the detentions, Ukraine has worked urgently to solve this matter," said Zerkal who insisted her country has given "Russia every opportunity to settle the issue by diplomatic means."
She described Russia's conduct as "a profound violation" of international law and demanded the urgent release of the sailors.