KYIV: Ukraine said Thursday it faced fierce fighting on the northeastern front line near Kupiansk, where Ukrainian officials urged civilian evacuations as Russia ramped up its assaults.

"Russians are trying to prevail (in the Kupiansk area) and break through our defence... the situation remains difficult but under control," Sergiy Cherevaty, spokesman for Ukraine's eastern forces, said on national television.

Kupiansk and the surrounding areas of Ukraine's Kharkiv region was recaptured by Kyiv's forces last September, but Moscow has since pushed back on the region.

Russia says advanced in northeast Ukraine in recent days

Local authorities have told residents of 37 settlements wedged between the town of Kupiansk and Russian frontlines to evacuate.

"The evacuation started yesterday, when the order was signed," the head of the Kupiansk city military administration Andriy Besedin said on national television.

Besedin said that residents could refuse to be evacuated but had to submit a written statement to authorities.

Local officials were also looking at forcing the evacuation of children "if the escalation continues and the shelling increases", Besedin said.