Moscow has made a string of gains on the front in recent months, pressing its manpower and weapons advantage on the battlefield as Kyiv waits for critical supplies of Western aid.

The Russian defence ministry said its army units had “liberated the village of Kyslivka in the Kharkiv region” and “Novokalynove in the Donetsk People’s Republic”.

Kyslivka is about 20km from the embattled Ukrainian stronghold of Kupiansk, while Novokalynove is about 10km north of Avdiivka, captured by Moscow in February.

Officials in Ukraine are worried Russia may be preparing a fresh offensive in the northeast, taking advantage of severe ammunition shortages in the Ukrainian army.

Ukraine’s commander-in-chief Oleksandr Syrskyi acknowledged in April that Kyiv had pulled back from three villages and was building a new line of fortifications to defend the front.

Separately, the Russian defence ministry said it had launched retaliatory strikes against Ukrainian energy and military facilities, after Kyiv reported a wave of aerial attacks overnight.

“In response to the Kyiv regime’s attempt to damage Russian energy facilities, this morning the armed forces of the Russian Federation launched a group strike against energy facilities and enterprises of Ukraine’s military-industrial complex,” it said.