Russia has started evacuating hundreds of civilians from occupied areas in south-eastern Ukraine, including families with children from a town housing workers at Europe’s largest nuclear power plant, raising fresh concerns about its safety.

The evacuations that started over the weekend come as Russian officials accuse Ukraine of stepping up drone strikes on its territory and in Russian-occupied Crimea, moves seen by analysts as preparations for a spring counteroffensive by Kyiv. Russia, in turn, has in recent weeks increased its own drone and missile attacks on Ukrainian cities.

The Russian-installed head of the occupied part of Zaporizhzhia region, which includes the eponymous nuclear power plant that has been under Russian control since March last year, on Friday announced a partial evacuation of 18 frontline settlements due, he claimed, to increased fighting in the area.

Yevgeny Balitsky said on Sunday that 1,552 people, including 632 children, had so far been relocated from two frontline cities and five districts. “People are also leaving dangerous areas on their own in their private vehicles,” he added.

In previous days, Balitsky said residents of these areas understood the need “to leave, today, to protect their lives and get away from shelling, from the line of combat,” adding that residents were being relocated further south, to places such as the Black Sea port city of Berdyansk.

On Sunday, Balitsky appeared to visit evacuees in Berdyansk, saying in a video that the first 1,000 people to be evacuated from the north had received housing there. He also addressed those people who chose to stay in dangerous areas, saying that doing so was “their right” but adding that “time will be the judge”.

The general staff of Ukraine’s armed forces confirmed the evacuation in a statement on Sunday. “Russian occupants are evacuating civilians . . . to local recreation centres in the settlements of Berdyansk and Prymorsk,” the general staff said.

Evacuation orders also affect the town of Enerhodar, which is close to the northern frontline. It is also home to many of the staff of the adjacent Zaporizhzhia nuclear power plant, Europe’s largest, that was seized by Russia early on in its full-scale invasion.

The International Atomic Energy Agency, which has experts present at the plant, on Saturday said it had been notified about the partial evacuation of Enerhodar residents, though had not witnessed it first-hand.

Operating staff remained on site at the plant, the agency said, but it expressed concern about the “recent increase in military presence and activity” in the area and resulting “tense, stressful, and challenging conditions for personnel — and their families”.

“The general situation in the area near the Zaporizhzhia nuclear power plant is becoming increasingly unpredictable and potentially dangerous,” the agency’s director Rafael Grossi said. “I’m extremely concerned about the very real nuclear safety and security risks facing the plant.”

The Russian-installed head of the plant, Yuriy Chernichuk, on Saturday denied that there was cause for concern. “The equipment is maintained in accordance with all necessary regulations and under strict control of radiation safety standards,” he said, adding that all units at the plant were in shutdown mode.

He said that evacuation orders for Enerhodar only concerned families with children, to protect “their psychological state”. He added: “There is no need to evacuate employees of the station and residents of the city now. Please remain calm.”

Ukraine’s nuclear power holding, Energoatom, in a Saturday statement also said that “there have been no changes in the operation of the Zaporizhzhia nuclear power plant”.

The number of sabotage and other attacks inside Russia have also increased in recent days, which some have seen as linked to the start of a counteroffensive. Two drones were shot down last week over the Kremlin, and a car bomb in the Nizhny Novgorod region severely injured a well-known pro-war nationalist author, Zakhar Prilepin.

Attack drones have also caused damage at several oil facilities in central Russia, and reconnaissance drones have either been spotted or shot down in several areas — including, on Sunday, near a military aircraft parts factory in Novosibirsk in Siberia.

Ukraine’s air defences have recently been boosted with sophisticated surface-to-air missiles provided by Nato countries, including two Patriot missile batteries that can intercept ballistic missiles, a capability Kyiv had not earlier had.

Mykola Oleshchuk, commander of Ukraine’s air force, boasted this weekend that his troops had two days earlier downed a Russian Kinzhal hypersonic ballistic missile for the first time. That type of missiles had previously eluded Ukraine’s traditional air defences, causing death and destruction in urban areas.