The two tankers, Virat and Kairos, were attacked off the coast of Turkey late Friday. On Saturday morning, one of them was hit again by an explosive device.
Modern naval drones successfully hit the ships, a source within Ukraine's SBU security service told AFP.
In an unverified footage shown to AFP by the source, two naval drones are seen traveling towards the two ships before exploding.
Both tankers are suspected of being part of Russia's so-called shadow fleet - aging oil tankers that Russia uses to circumvent Western sanctions. The EU has imposed sanctions on a total of 557 ships suspected of belonging to the so-called shadow fleet, including banning them from calling at EU ports. According to the Reuters news agency, both tankers in question are among these.
The crew from the ships are reported to be safe.
