United Nations (UN) Secretary-General Antonio Guterres on Tuesday expressed his concern over the incident involving Ukrainian and Russian vessels near the Crimean Peninsula in the Black Sea at the approach to the Kerch Strait.

Three Ukrainian Navy vessels have illegally crossed the Russian border and intruded into Russia's territorial waters, November 25 2018. [Photo:IC]

In a statement issued by his spokesperson Stephane Dujarric, the secretary-general underlined "the immediate need to avoid any risk of further escalation of the situation."

"The secretary-general urges both parties to exercise maximum restraint and to take steps without delay to contain this incident and reduce tensions through all available peaceful means in accordance with the Charter of the United Nations," said the statement.

"He underscores the need to fully respect the rights and obligations of all concerned parties under relevant international instruments. The sovereignty and territorial integrity of Ukraine, within its internationally recognized borders, in accordance with relevant General Assembly and Security Council resolutions, must also be fully respected," the statement added.

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.

Six Ukrainian military sailors were wounded in the attack and two of them were in serious condition, the Ukrainian Navy said.

Russia's Federal Security Service (FSB) said that three Ukrainian ships, namely Berdyansk, Nikopol and Yany Kapu, breached the Russian border and conducted dangerous maneuvers in spite of orders of the accompanying vessels from the FSB and Russia's Black Sea Fleet.

An emergency meeting of the UN Security Council was called for on Monday morning over the escalating situation.