Radev confirms that one ship has sunk. He plans to summon Russia's ambassador to the country over the "unacceptable" attacks.
European Commission President Ursula von der Leyen condemns the attack.
“The Black Sea has become another front in the escalation of Russia's war in Ukraine,” she writes on X.
One crew member from the sunken ship has been rescued, Radev said, but gave no details about the rest of the crew.
The crew of one of the ships, registered in Odesa and sailing under the Maltese flag, have been rescued and are receiving medical treatment for minor injuries.
Last week, two other ships were attacked in the Black Sea, one of which sank. It is still unclear who was behind the attacks.
Radev says he will speak with NATO Secretary General Mark Rutte and seek support for an investigation into the attacks.
