On day 101 of the war, Ukraine said Russia was doing everything it could to take control of the key eastern city of Severodonetsk.

"The Russian army is throwing all its power, all its reserves in this direction," said Serhiy Haidai, the regional governor.

The city has seen extremely fierce fighting in recent days as Russian troops try to take control of the entire Luhansk region - one of two regions which make up the part of eastern Ukraine known as the Donbas.

Mr Haidai said earlier that Ukrainian forces had managed to retake some of Severodonetsk from Russian forces, adding that Russia had suffered huge losses.

The Russian bombardment of the city has been compared to the battle of Mariupol, which was all but destroyed by a relentless Russian assault.

Elsewhere in the Donbas, fighting sparked a major fire at a famous wooden monastery - the Sviatohirsk Lavra Monastery in the Donetsk region.

The Ukrainian Orthodox Church said the flames had engulfed the monastery's main shrine.

"Another crime of Russian barbarians for whom there is nothing sacred," Ukrainian army officer, Yurii Kochevenko, said on Facebook.

A Ukrainian government tweet shows the fine old monastery intact, before it was hit.

Russia blamed Ukrainian "nationalist" troops for setting fire to the building.

Russia's focus on the Donbas does not mean the shelling has stopped in other parts of the country.

To the south, the important Black Sea port city of Mykolaiv was one of the first cities attacked when the invasion began. Russian forces were pushed back from the city limits.

But there is still shelling every day there, and if Russia accomplishes its goal of capturing the Donbas it could refocus its efforts to the south and try once again to take Mykolaiv.

Despite the constant danger, residents of the region remain defiant.

"Thank God, we are holding on... they [the Russians] should know better than loitering on our land," Natalia Panashii told the BBC's Laura Bicker on a recent visit.