Ukrainian President Volodymyr Zelensky has urged Russian troops to flee for their lives after his forces launched an offensive to retake southern Ukraine, but Moscow said it had halted the attack in its tracks and inflicted heavy losses on Kyiv.
Ukraine said on Monday its ground forces had gone on the offensive in the south for the first time after a period of striking Russian supply lines, in particular bridges across the strategically-important River Dnipro, and ammunition dumps.
In a late night address on Monday, Zelensky called on Russian forces to go home or be chased home.
"If they want to survive - it's time for the Russian military to run away. Go home," he said.
"Ukraine is taking back its own (land)," Zelensky said, adding that he would not disclose Kyiv's precise battle plans, but that his armed forces were doing their job.
The new offensive comes after several weeks of relative stalemate in a war that has killed thousands, displaced millions, destroyed cities and fueled a global energy and food crisis amid unprecedented Western economic sanctions on Russia.
"If they want to survive - it's time for the Russian military to run away. Go home."
Volodymyr Zelensky
Russia captured swathes of Ukraine's south near the Black Sea coast in its early phase, including in the Kherson region which lies north of the Russian-annexed Crimean peninsula.
Ukraine, now armed with sophisticated Western-supplied weapons, sees retaking the region as crucial to prevent Russian attempts to seize more territory further to the west that could eventually cut off its access to the Black Sea.
Heavy fighting
Oleksiy Arestovych, a senior Ukrainian presidential adviser, said Russian defenses in the Kherson region had been "broken through in a few hours." It was unclear which line of Russian defense, of which there are many, he was referring to.
Arestovych also said Ukrainian forces were shelling ferries that Russia was using to supply a pocket of territory on the west bank of the Dnipro river in the Kherson region.
Britain, a close ally of Ukraine, said on Tuesday that Kyiv had stepped up its artillery barrage across the entire southern front, but said it was not yet possible to confirm the extent of Ukrainian territorial advances.
Vitaly Kim, governor of the Mykolaiv region, told Ukrainian TV: "Heavy fighting is going on. Our military is working around the clock. Liberation of the Kherson region is coming soon."
Unverified reports, images and footage on social media suggested that Ukrainian forces may have taken back some villages and destroyed some Russian targets in the south.
Russia's RIA news agency reported that the Russian-controlled town of Nova Kakhovka had been left without water or power after a Ukrainian missile strike.
However, Russia's defense ministry said the Ukrainian offensive had been halted in its tracks.
It said in a statement that Ukrainian forces had attempted to go on the offensive in three different directions in the southern Mykolaiv and Kherson regions, but had lost some 560 military personnel, 26 tanks and two warplanes.
"Another attempt by the enemy to go on the offensive has fallen apart," it said.
Reuters could not verify the battlefield reports.
Ukraine's Suspilne public broadcaster reported explosions in the Kherson area on Tuesday, while city residents reported in social media posts gunfire and explosions. They said it was not clear who was firing.
A Russian-installed official in Kherson said Russian forces had discovered a Ukrainian sabotage group in the city and destroyed it.
Nuclear plant in focus
Heavy Russian shelling of Kharkiv, Ukraine's second city, was also reported.
At least five people were killed and seven were wounded, the mayor of Kharkiv, Ihor Terekhov, wrote on the Telegram messaging app.
Russia denies deliberately targeting civilians though its attacks have devastated Ukrainian towns and cities.
Russia invaded Ukraine on Feb. 24 to wage what it said was a "special military operation" to rid the country of nationalists and protect Russian-speaking communities. Ukraine and its allies describe it as an unprovoked war of aggression.
The Zaporizhzhia nuclear power plant in central southern Ukraine, captured by Russian troops in March but still manned by Ukrainian staff, has been a hotspot in the conflict, with both sides trading blame for shelling in the vicinity.
Russian-installed authorities accused Ukrainian troops of firing two shells that exploded near a spent fuel storage building at the plant, the TASS news agency reported. There was no immediate comment from the Ukrainian side.
A mission from the International Atomic Energy Agency (IAEA) is headed to the nuclear plant, Europe's largest, and is due later this week to inspect and assess any damage.
Led by IAEA chief Rafael Grossi, the mission will evaluate working conditions and check safety and security systems, the Vienna-based organization said.
The European Union is examining fresh ways to pressure Russia to end the war, but France and Germany warned on Tuesday against proposals to ban tourist visas for Russians, saying such a move - strongly backed by the Baltic states - would be counter-productive.
The Kremlin condemned the proposals as "irrational."