Russian forces attacked energy infrastructure in Ukraine's northeastern Sumy region, cutting power in some districts and forcing authorities to resort to back-up power systems, local authorities said on Tuesday.

The attack dealt damage in Konotop, Okhtyrka and Sumy districts of the region and the critical infrastructure facilities were using back-up power systems, regional officials said via the Telegram messaging app.

Sumy water supply facilities said that the attack cut power to them at night, prompting the switch to emergency power supply.

Sumy's acting mayor Artem Kobzar said there were no casualties in the city and that energy workers were dealing with the attack's aftermath.

The regional authorities said air defences shot down 16 drones over the region.

The Ukrainian air force said Russia launched 51 drones to attack the country overnight and that it had shot down 34 of them after the air defence worked in five regions.