Ukrainian President Volodymyr Zelenskyy has vowed to strengthen his country's air defenses, as Russia keeps up its attacks on many parts of the country.

Russia continued to strike with drones and missiles on Thursday and Friday, targeting infrastructure in Kyiv and elsewhere.

Mayor Vitali Klitschko said drones had been shot down, but falling debris had damaged buildings.

Russia's defense ministry said on Friday its forces conducted large-scale assaults on electricity facilities supporting Ukraine's military command and defense industry.

Meanwhile, fierce fighting is raging in the eastern province of Donetsk.

News footage taken on Friday at a field hospital in the province showed injured troops being carried on stretchers while being treated by medical workers.

Zelenskyy referred to the situation in eastern parts of Ukraine in a video address released on Friday. He said Ukrainians are "slowly advancing" in some frontline areas.

He said, "This year, we not only maintained our air defenses, but we made them stronger than ever. But in the New Year Ukrainian air defense will become even stronger, even more effective."

He reiterated his resolve to counter Russian attacks, as his country continues to receive military supplies from Western countries.