KIEV, Nov. 28 (Xinhua) -- The Ukrainian Foreign Ministry said on Wednesday it has sent a note to Russia urging it to release the Ukrainian sailors who were detained during the tensions in the Sea of Azov.

"We have renewed the categorical requirement to the Russian side to immediately release from custody captured Ukrainian citizens and ensure their safe return to their homeland," the ministry said in a statement.

On Sunday, the Ukrainian Navy said that Russian forces opened fire and seized three Ukrainian ships near the Kerch Strait which separates the Black Sea and the Sea of Azov.

Russia's Federal Security Service said that three Ukrainian ships, namely Berdyansk, Nikopol and Yany Kapu, breached the Russian border and conducted dangerous maneuvers despite calls from Russian vessels that accompanied them.

The General Staff of the Ukrainian Armed Forces said that more than 20 Ukrainians were detained during the tensions.