President of Ukraine Petro Poroshenko and NATO Secretary General Jens Stoltenberg, during a telephone conversation, have agreed to urgently convene an emergency meeting of the Ukraine-NATO Commission because of the act of Russian aggression in the Sea of Azov.

"Poroshenko and Stoltenberg have agreed to urgently convene an emergency meeting of the Ukraine-NATO Commission because of the aggression of Russia," the press service of the head of the Ukrainian state said on Monday.

Poroshenko informed Stoltenberg about the incident and Ukraine's actions in response, including plans to declare martial law, it said.

The Ukrainian leader also called for greater international pressure on Russia to force it to free the Ukrainian sailors and vessels immediately.

Stoltenberg voiced support for Ukraine's territorial integrity and sovereignty and urged Russia to respect international law and freedom of navigation in the Sea of Azov and the Black Sea.

The parties agreed to continue top-level contacts.

The Ukrainian mission to NATO said on Twitter that a NATO-Ukraine Commission would meet in Brussels at the level of permanent representatives on Monday.