KIEV, Dec. 13 (Xinhua) -- Ukraine's President Petro Poroshenko on Thursday discussed the situation in the Kerch Strait with NATO Secretary General Jens Stoltenberg, the presidential press service said.

During the meeting in Brussels, Poroshenko urged Stoltenberg to launch NATO mission for monitoring air and sea space in the Black Sea.

The reinforcement of NATO's permanent presence in the Black Sea is needed to prevent further escalation of the tensions and ensure security in the region, Poroshenko said.

For his part, Stoltenberg said that NATO is concerned over the situation in the Sea of Azov and the surrounding waters and urged Russia to release captured Ukrainian ships and sailors.

On Nov. 25, three Ukrainian ships and more than 20 sailors attempting to sail through the Kerch Strait from the Black Sea to the Sea of Azov were seized by Russian forces for allegedly violating the Russian border.

The Ukrainian Navy said that it had informed Russia in advance of the passage, while Russia said it had received no such report and the ships ignored multiple warnings by the Russian border guards.