Ukraine hit two tankers used by Russia to export oil while skirting Western sanctions with marine drones in the Black Sea, an official from the Security Service of Ukraine (SBU) said Saturday.

The joint operation to hit the so-called "shadow fleet" vessels was run by the SBU and Ukraine's navy, the official said on condition of anonymity.

Turkish authorities said that blasts rocked two shadow fleet tankers near Turkey's Bosporus Strait on Friday causing fires on the vessels, and rescue operations were launched for those on board.

The SBU official said both tankers -- identified as the Kairos and Virat -- were empty and on their way to the port of Novorossiysk, a major Russian oil terminal.

"Video (footage) shows that after being hit, both tankers sustained critical damage and were effectively taken out of service. This will deal a significant blow to Russian oil transportation," the official said.

They did not say when the strikes took place.

Ukraine has consistently called for tougher international measures for Russia's "shadow fleet," which it says is helping Moscow export vast quantities of oil and fund its war in Ukraine despite Western sanctions.