Ukrainian forces have responded to Russian efforts to expel them from one part of Russian territory by launching a large number of attacks on another border area, using drones, artillery and troops.

Just as Ukrainian forces are losing their grip on the pocket of Russia's Kursk region they captured last year, they have staged a little-publicised incursion into the adjacent Belgorod region, according to Russian military bloggers.

A Russian drone attack injured four people and sparked a large fire in a hotel and restaurant complex and other buildings late on Friday in the southeastern Ukrainian city of Dnipro, the regional governor said.