Two Russian regions bordering Ukraine ordered more evacuations on Monday as Moscow battled to contain an unprecedented push onto its territory.
Ukraine sent troops into Russia last week in its biggest cross-border operation since Moscow launched its invasion in February 2022 and the most significant by a foreign army since World War II.
Authorities in the Kursk region announced they were widening their evacuation area to include Belovsky district, home to some 14,000 people. The neighbouring Belgorod region said it was evacuating its border district of Krasnoyaruzhsky.
"For the health and security of our population, we're beginning to move people who live in Krasnoyaruzhsky to safer places," Belgorod region governor Vyacheslav Gladkov said on Telegram.
The assault on Kursk had already led to 76,000 people being ordered out.
A top Ukrainian official told AFP over the weekend that the operation was aimed at stretching Russian troops and destabilising the country after months of slow Russian advances across the frontline.
The assault appeared to catch the Kremlin off guard. Russia's army rushed in reserve troops, tanks, aviation, artillery and drones in a bid to quash it.
But the army on Sunday conceded that Ukraine had penetrated up to 30 kilometres (20 miles) into Russian territory in places.
In a briefing, the defence ministry said it had "foiled attempts" by Ukraine's forces to "break through deep into Russian territory" using armoured vehicles.
But it said some forces were near the villages of Tolpino and Obshchy Kolodez, some 25 kilometres and 30 kilometres from the Russia-Ukraine border.
A Ukrainian security official told AFP, on condition of anonymity, that "the aim is to stretch the positions of the enemy, to inflict maximum losses and to destabilise the situation in Russia as they are unable to protect their own border".
The Ukrainian official said thousands of Ukrainian troops were involved in the operation.
Russia's defence ministry said on Monday that its air defence systems had destroyed 18 Ukrainian drones -- including 11 over the Kursk region.
- Helicopters 'over your head' -
On Sunday, each country blamed the other for a fire at the Russian-occupied Zaporizhzhia nuclear plant in southern Ukraine. Both sides -- and the UN's nuclear watchdog -- said there was no sign of a nuclear leak.
"No impact has been reported for nuclear safety," said the International Atomic Energy Agency, which has experts at the site. Kyiv and Moscow said there had been no rise in radiation levels.
In a later statement, the IAEA said it had requested "immediate access to the cooling tower to assess the damage".
A Moscow-installed official, Vladimir Rogov, said the blaze has been "completely extinguished" in a Telegram post Monday.
The plant's Russian-installed operator said on Monday that it was working normally following the incident and that all six reactors remained in "cold shutdown".
- 'It's scary' -
Russia's emergency situations ministry said on Sunday that over 44,000 residents in the Kursk region have applied for financial assistance, TASS news agency reported.
At an aid centre in Moscow, 28-year-old midwife Daria Chistopolskaya was critical of the response.
"I think that the state does not care enough about such people, and people themselves should help each other in these kinds of situations," she told AFP.
Russia's rail operator organised emergency trains from Kursk to Moscow, around 450 kilometres away, for those fleeing.
"It's scary to have helicopters flying over your head all the time," said Marina, refusing to give her surname, who arrived by train in Moscow on Sunday. "When it was possible to leave, I left."
Kursk regional governor Alexei Smirnov conceded on Sunday that the situation was "difficult".
Across the border in Ukraine's Sumy region, AFP journalists on Sunday saw dozens of armoured vehicles daubed with a white triangle -- the insignia apparently being used to identify Ukrainian military hardware deployed in the attack.
- 'Taste' of war -
At an evacuation centre in the regional capital of Sumy, 70-year-old retired metal worker Mykola, who fled his village of Khotyn some 10 kilometres from the Russian border, welcomed Ukraine's push into Russia.
"Let's let them find out what it's like," he told AFP. "They don't understand what war is. Let them have a taste of it."
Analysts think Kyiv may have launched the assault to try to relieve pressure on its troops in other parts of the front line.
But the Ukrainian official said: "Their pressure in the east continues, they are not pulling back troops from the area," even if "the intensity of Russian attacks has gone down a little bit".
The Ukrainian official said he expected Russia would "in the end" stop the incursion.
Ukraine was bracing for a large-scale retalliatory missile attack, including "on decision-making centres" in Ukraine, the official said.
By Ania Tsoukanova With Jonathan Brown In Sumy