Separately, Zelensky said almost 300 drones and 18 missiles had targeted cities across the country overnight, causing a major power outage near Kyiv.
The city’s mayor Vitali Klitschko said air defences were in operation during what the military said had been a missile attack. The CEO of energy company Yasno said the whole city had gone into “emergency shutdowns” as a result.
Parts of the capital had already faced days without heating and electricity in freezing temperatures due to strikes last week.
Zelensky said four people were killed in a missile strike “without any military purpose whatsoever” on a postal terminal in Korotych, Kharkiv, in which the region’s governor said 10 people had been injured.
Elsewhere, the governor of Donetsk Vadym Filashkin said two were killed in strikes across the region, while officials in Odesa said six people were injured by strikes which damaged homes, energy facilities, a hospital and a kindergarten.
Kyiv said it had also launched its own attack overnight on a drone manufacturing plant in Russia’s western Rostov region.
The latest attacks came two days after Russia’s full-scale invasion hit its 1,418th day on Sunday – the same length of the Soviet army’s participation in World War Two.
The EU’s ambassador to Ukraine Katarina Matheronva wrote on social media: “Back then, the USSR was attacked, fought back, and – thanks to massive Western support – ended the war victorious… Today, Putin chose this war. Planned it. Launched it. Owns it.”