Ukrainian forces claimed to have 'broken through' Russian defences on Monday amid a new counter-offensive in the Kherson region.
The operation, launched yesterday, is aimed at pushing Russian troops back across the Dnipro river and retaking the occupied city of Kherson.
Intense battles are currently raging between Ukrainian and Russian forces across almost all of the southern region, according to the Ukrainian presidency.
Ukrainian forces broke through Russia's first line of defence on the outskirts of Kherson, capturing an industrial site reportedly being used as an army base, Ukrainian local media reported on Monday.
While independent verification of battlefield action has been difficult, the UK Defence Ministry said in an intelligence report that several Ukrainian brigades had stepped up their artillery fire in front-line sectors across the south of the country.
Ukraine’s presidential office reported that “powerful explosions continued during the day and night in the Kherson region. Tough battles are ongoing practically across all” of the area.
Ukrainian forces, the office said, destroyed ammunition depots and all large bridges across the Dnipro river that are vital to bringing supplies to Russian troops.
Speaking to CNN in the evening Monday, an anonymous source within the Ukrainian military said its forces had also recaptured four villages in Kherson Oblast.
Russia's military claims that it successfully repelled an offensive by Ukrainian troops, who suffered "heavy losses" as a result.
Euronews cannot independently verify any of these claims.
Kyiv called on all civilians in the Kherson Oblast to evacuate the area, with its forces continuing to press into the area and harangue Russian positions on Tuesday.
Kherson, with a pre-war population of 280,000, was the first major Ukrainian city to fall into Russian hands at the start of the invasion in February.
The wider region is strategically valuable. Alongside being a hub of Ukrainian agriculture, it borders the Russian-controlled Crimean peninsular, which Russia has used as a rear base for the invasion.
The huge new offensive follows a series of disruptive Ukrainian attacks against Russian forces and supply lines in the south, especially in Crimea where Russia has lost warplanes and military stores in acts of sabotage.
On Monday, Ukraine's forces were reportedly shelling ferries used by Russia to supply a pocket of territory it controls on the west bank of the Dnipro river in the Kherson region.
In his nightly video address, Ukrainian President Volodymyr Zelenskyy urged Russian troops to flee, saying Ukraine's military would chase them back "to the border."
"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."
The Russian defence ministry claimed Ukrainian troops had tried to push into Kherson, but sustained significant casualties, the country's state-owned RIA news agency reported.
The "enemy's offensive attempt failed miserably", it said.
Earlier on Monday, a spokeswoman for Ukraine's Operational Command South, Natalia Humeniuk, announced that Kyiv had launched a counter-offensive in the south and its forces were attacking "in many directions."
The Ukrainian military grouping "Kakhovka" said on Facebook it had seen a unit of pro-Russian separatist fighters retreating from their positions in the region, with Oleksyy Arestovych a senior advisor to Zelenskyy saying Russian defences had been "broken through in a few hours."
Again this is unverifiable by independent sources.
A major counter-offensive to liberate the southern region of Ukraine under Russia's control has been anticipated since July, following remarks by Ukraine's top brass that they had ordered the area's liberation.
"Today, there were powerful artillery attacks on enemy positions ... throughout the territory of the occupied Kherson region," Sergey Khlan, an advisor to the regional governor, told Ukrainian media outlets on Monday.
"This is the announcement of what we have been waiting for since spring: it is the beginning of the end of the occupation of the Kherson region," Khlan added.
With the war in Ukraine now in its sixth month, the coming weeks may prove decisive.
Ukraine has vowed to drive Russians from the territory they have seized since the start of the invasion, including the southern region of Kherson, while Moscow has pledged to hold on to the occupied areas and take more ground around the country.
The Ukrainians have used American-supplied rocket launchers such as HIMARS to strike bridges and military infrastructure in the south, forcing Russia to divert its forces from the Donbas in the east to counter the new threat.
A key bridge near Kherson was destroyed by the Ukrainian army in the lead-up to the counter-offensive, cutting traffic across it and raising potential supply problems for Russian forces in the area.
Russia can still use a second crossing on the Dnipro to ferry supplies and reinforcements to its troops in Kherson, which lies just north of the Crimean Peninsula -- annexed by Russia in 2014 -- but Ukraine's strikes have shown Russia's vulnerability and weakened its hold on the region.
While the bulk of Russian and Ukrainian military assets are conсentrated in the Donbas, the industrial region of mines and factories, both sides hope to make gains elsewhere.
Moscow-appointed occupation officials in Kherson have talked about holding a referendum on joining Russia as early as September. Those plans hinge on Russia's ability to win full control of those areas by then.