Drones hit two ships in Bulgaria's economic zone in the Black Sea, prompting president Iliana Yotova to cancel a planned visit to Veliko Tarnovo, the president's press office said.

The head of state had been due to attend an event at 11:00 presenting the results of archaeological digs and restoration work on Trapezitsa hill.

Prime minister Rumen Radev called a meeting with officials over the strike on the ships, the government's press office said.