The fresh call on civilians to flee the town of Borova, which had an estimated pre-war population of around 5,000 people, points to the deterioration of Ukrainian defenses.

"Due to the security situation, the decision to forcibly evacuate children with their families from the village of Borova in the Kharkiv region was approved," authorities in Kyiv said.

Moscow's forces were pushed back in the Kharkiv region, which borders Russia, several months after their invasion in February 2022 but have recently been making some gains.

"The evacuation to safe regions will take place within 60 days. A reception and assembly center will be deployed to carry out the evacuation," the statement announcing the evacuations said.

Across the sprawling front in eastern Ukraine, its under-resourced and outgunned troops have been ceding ground to Russian forces, particularly in the industrial Donetsk region.

The governor of the Donetsk region earlier said all children had been removed from the frontline town of Myrnograd and just several dozen remained in the nearby transport hub of Pokrovsk, the main target of Russian advances.

Authorities in the Zaporizhzhia region, which the Kremlin claimed to have annexed alongside Donetsk and two others, meanwhile said Wednesday that two men aged 40 and 73 had been killed in a drone attack.