Bulgaria on Wednesday said Russia was likely behind drone attacks that struck four ships in the Black Sea in the past week, sinking two, but there was no way of proving Moscow's culpability.

President Iliana Yotova has called for an immediate halt to hostilities in the Black Sea and a moratorium on drone attacks against commercial and civilian infrastructure, as two ships were struck in the area, BNT reported. Yotova thanked the rescue teams that worked throughout the night to save sailors from one of the vessels attacked in the Black Sea.

After numerous lethal drone attacks in NATO waters, Black Sea countries seek alliance support and EU leaders discuss how to restore safe passage.

Russian Ambassador Eleonora Mitrofanova told Prime Minister Rumen Radev that Moscow had no information about attacks on ships in the Black Sea, although an investigation would establish whether that account was accurate, Radev said during a hearing in the National Assembly. “I also summoned the Russian ambassador to the Council of Ministers for talks.

New drone strikes on two ships in the Black Sea pose questions for the future of Russian and Ukrainian food exports to already struggling world markets.