Russian missiles pounded the southern Ukrainian port city of Mykolaiv early on Sunday, killing the owner of a major grain exporter, while a drone strike on Russia's Black Sea naval base in Sevastopol was launched from within the city in a "terrorist attack," a Russian lawmaker said.

Oleksiy Vadatursky, founder and owner of agriculture company Nibulon, and his wife were killed in their home, Mykolaiv Gov. Vitaliy Kim said on Telegram.

Headquartered in Mykolaiv, a strategically important city that borders the mostly Russian-occupied Kherson region, Nibulon specializes in the production and export of wheat, barley and corn, and has its own fleet and shipyard.