Three vessels came under drone attack off Turkey's northern coast on Thursday, Reuters said, citing the maritime agency Tribeca.
The vessel James II, sailing under the flag of Palau, was located about 80 kilometers north of the Turkeli district at the time of the incident.
The tankers Altura and Velora, both operating under the flag of Sierra Leone, were attacked in the same area while conducting ship-to-ship cargo transfer operations.
Video footage published after the incident appears to show that two of the drones failed to explode. One drone struck a tanker without detonating, while another remained floating alongside one of the vessels.
Reports identified the drones as Ukrainian Magura V5/V7 naval drones.
Rescue boats were dispatched to the area following the attacks.
All crew members aboard the tankers were reported safe and unharmed.
Authorities have not yet released information about possible damage to the vessels.
In March, Ukrainian drones reportedly struck the Turkish-owned oil tanker ALTURA about 15 nautical miles from the Bosphorus.
The tanker was transporting Russian crude oil at the time of the attack.
The vessel was carrying 140,000 tons of oil and a crew of 27 Turkish nationals. No one was injured, although the tanker sustained damage.