"A drone struck the chimney of the Auvere power plant. No one was injured in the incident," Estonia's internal security service said in a statement, adding that "the drone entered Estonian airspace from Russian airspace".

"These are the effects of Russia's large-scale war of aggression," said ISS Director General Margo Palloson, expressing concern about "the occurrence of such incidents in the future".

The ?incidents occurred at about ?the same time that ?a Ukrainian drone attack set fire to ?oil facilities at Russia's Baltic Sea port of Ust-Luga, a major petroleum export hub about 25 kilometres from the border with Estonia.

Russian air defences downed 389 incoming Ukrainian drones, Russia’s defence ministry said Wednesday, in what was the largest reported overnight attack on Russian regions and Crimea since Moscow’s forces invaded Ukraine more than four years ago.

It came a day after Russia fired almost 1,000 drones and 34 missiles at Ukraine in the space of 24 hours, extending its usual nighttime barrage into daylight hours in one of its biggest aerial attacks of the war. At least six people were killed and around 50 people were injured, Ukrainian authorities said.