A Russian-installed official in the town of Nova Kakhovka said on Tuesday residents of around 300 houses had been evacuated after a nearby dam was breached, state-owned news agency TASS reported.
TASS also quoted Nova Kakhovka's Russian-installed mayor Vladimir Leontyev as saying that part of the town had been disconnected from power supplies for safety reasons.
Millions of liters of water burst through a gaping hole in a Russian-controlled dam on Tuesday, flooding a swathe of the war zone in southern Ukraine, threatening scores of villages and cutting off water supplies.
Unverified videos on social media showed water surging through the remains of the dam with bystanders expressing their shock, sometimes in strong language. Water levels raced up by meters in a matter of hours.
The dam, 30 meters (yards) tall and 3.2 km (2 miles) long and which holds water equal to the Great Salt Lake in the US state of Utah, was built in 1956 on the Dnipro River as part of the Kakhovka hydroelectric power plant.
It also supplies water to the Crimean peninsula, annexed by Russia in 2014, and to the Zaporizhzhia nuclear plant, which is also under Russian control and which gets cooling water from the reservoir.
The International Atomic Energy Agency (IAEA) said there was no immediate nuclear safety risk at the plant due to the dam failure but that it was monitoring the situation closely. The head of the plant also said there was no current threat to the station.
Ukrainian President Volodymyr Zelensky blamed Russia for the damage.
"The destruction of the Kakhovka hydroelectric power plant dam only confirms for the whole world that they must be expelled from every corner of Ukrainian land," Zelensky wrote on the Telegram messaging app.
Ukraine's military said that Russian forces blew up the dam.
Russian terrorists. The destruction of the Kakhovka hydroelectric power plant dam only confirms for the whole world that they must be expelled from every corner of Ukrainian land. Not a single meter should be left to them, because they use every meter for terror. It’s only… pic.twitter.com/ErBog1gRhH
— Володимир Зеленський (@ZelenskyyUa) June 6, 2023
"Tonight at 02:50, Russian terrorists carried out an internal detonation of the structures of the Kakhovskaya HPP (hydroelectric power plant)," Zelensky said after an emergency meeting of senior officials.
He said "a set of international and security measures was agreed upon (at the meeting) to hold Russia accountable for this terrorist attack."
In a later video address to a summit of European countries in the Bucharest Nine group, Zelensky said Russia had controlled the dam and hydroelectric plant for over a year.
"It is physically impossible to blow it up somehow from the outside - with shelling. It was mined. It was mined by the Russian occupiers and blown up by them," he said.
Russian-installed officials in Kherson said Ukraine struck the dam at 11 p.m. GMT several times, destroying the hydraulic valves of the hydroelectric power station but said the dam was not totally destroyed.
"We ask all residents of coastal settlements to be ready for evacuation," the Russian-controlled region said. "Emergency and special services of the region are in full readiness and will provide all necessary assistance."
Reuters was unable to immediately verify the battlefield accounts from either side.
It was not immediately clear how the flood waters would affect Ukraine's long-planned counter-offensive against Russian forces who are dug in across southern and eastern Ukraine.
Jewish communities along the river prepare
The Federation of Jewish Communities of Ukraine announced that it was closely monitoring the situation in light of the dam break and was preparing to provide large-scale assistance.
Rabbi Yossi Wolf, Chabad emissary and rabbi of the city of Kherson, stated that "The rescuers in the city say that the peak of the flooding will be around 12 o'clock [Tuesday]. Hundreds of thousands of homes are going to be totally damaged. The entire part close to the river is going to be flooded."
"We are working with full vigor and making sure, with the help of the federation, to reach all those Jews who live on the river bank and evacuate them to the higher part of the city so that their lives are not in danger. We are also checking where individual Jews live in the small villages in the area in order to rescue them as well."
Ukrainian attacks
Russian President Vladimir Putin sent troops into Ukraine on Feb. 24 last year in what the Kremlin expected to be a swift operation, but its forces suffered a series of defeats and regrouped in the country's east.
Tens of thousands of Russian troops dug in over the winter, besieging Bakhmut for months and bracing for an expected Ukrainian counter-attack to try to cut Russia's so-called land bridge to the Crimean Peninsula.
Russia says it thwarted a major Ukrainian attack in the Donetsk region over the weekend and on Tuesday the defense ministry said a fresh Ukrainian assault had also been repelled.
Russian forces inflicted huge personnel losses on attacking Ukrainian forces and destroyed 28 tanks, including eight Leopard main battle tanks and 109 armored vehicles, it said. Total Ukrainian losses amounted to 1,500 troops.
"Having suffered heavy losses the day before, the Kyiv regime reorganized the remnants of the 23rd and 31st mechanized brigades into separate consolidated units, which continued offensive operations," the ministry said on Telegram.
"A complex fire defeat was inflicted by army forces, assault and operational-tactical aviation, missile forces and artillery, as well as heavy flamethrower systems."
There was no immediate comment from Kyiv about Russia's assertions. Russia and Ukraine have often made claims of inflicting heavy human losses on each other which could not be verified.
The Washington Post reported that some US officials thought Ukraine's counter-offensive was underway, but White House national security spokesperson John Kirby declined to comment on whether this was the case.
"I'm not going to be talking for the Ukrainian military," he told a briefing, adding that the United States had done "everything we could ... to make sure that they had all the equipment, the training, the capabilities to be successful."
The success or failure of a counteroffensive, expected to be waged with billions of dollars worth of advanced Western weaponry, is likely to influence the shape of future Western diplomatic and military support for Ukraine.
Ukrainian Foreign Minister Dmytro Kuleba told Reuters on Monday that Ukraine now had enough weapons for a counteroffensive but declined to comment when asked whether it had begun.
In its evening report on Monday, Ukraine's General Staff made no mention of any large-scale offensive, nor did it suggest any deviation from the usual tempo or scope of fighting along front lines that have not changed significantly for months.
Deputy Defense Minister Hanna Maliar said on Telegram that Ukraine was "shifting to offensive actions" along parts of the front but dismissed suggestions of a major operation.
Writing on Telegram, Russia's Wagner militia leader Yevgeny Prigozhin said Moscow's claims of huge Ukrainian losses were "simply wild and absurd science fiction."
Russia now controls at least 18% of internationally recognized Ukrainian territory and has claimed four more regions of Ukraine as Russian territory after annexing Crimea in 2014.
Jerusalem Post Staff contributed to this report.