Russian shelling killed four people in the eastern Ukraine region of Donetsk, authorities said Monday, as Moscow's forces aim to push deeper into the war-battered industrial region.

The region's governor said attacks late Sunday on the mining town of Siversk, which is flanked by Russian forces, had claimed the four lives.

"The city was shelled yesterday evening with multiple rocket launchers. It has now been established that four men aged 36 to 86 died as a result of this shelling," Vadym Filashkin wrote on social media.

Siversk, which had an estimated pre-war population of 11,000 people, has come under persistent Russian shelling since Moscow invaded Ukraine in February 2022.

Russia claimed to have annexed the entire Donetsk region in September 2022 despite not fulling controlling the region.

Officials have warned that the eastern front line has become increasingly precarious as Ukraine struggles to secure more arms from allies and recruit more troops.