Ukraine has carried out a drone strike on Belgorod dam that led to flooding in the southern Russian region and cut off several Moscow units.

Water gushed from the damaged reservoir, disrupting Russian logistics and stranding troops stationed on the Ukrainian side of the border in Vovchansk.

"The main thing is that the enemy's logistics have become significantly more complicated," a spokesman for the 16th Army Corps said.

"So the units that managed to cross the Siverskyi Donets have effectively been cut off from their main forces.

"So we're expecting the [prisoner of war] exchange pool to be replenished," it added, referring to the potential capture of stranded Russian troops.

Vovchansk was occupied by Russian troops until September 2022, when Ukrainian troops staged a successful counter-offensive to liberate the town.

Heavy fighting resumed again in May last year, forcing thousands of residents from their homes.

Col Robert Brovdi, commander of Ukraine's unmanned systems forces, confirmed on Sunday that Ukrainian forces had carried out the strike.

"The Belgorod Reservoir cracked today. Since the moment of the magical kick, the level has dropped by 100cm (3ft)," he wrote on Facebook.

"The operation was named 'Hang in there, dam!', but as the worms' [Russians'] intelligence shows, the dam is a little messed up," he added.

According to Russian regional authorities, the dam was damaged after several strikes between Oct 24 and 26.

On Saturday, Vyacheslav Gladkov, Belgorod's governor, reported that the dam had been struck by a Ukrainian drone.

"We understand that the enemy may attempt to strike again and destroy the dam," he said, warning that 1,000 people could be at risk if the structure is destroyed.

As of Monday, the water was flowing uncontrollably, according to verified video footage.

Before the dam strike, Ukraine's 16 Army Corps said Russian activity near Vovchansk had increased owing to warm weather.

This hardened the ground and led to shallower rivers in the region, making logistics easier for the Russians.

But after the strike, the water surged into the Siverskyi Donets River, reportedly flooding Russian bunkers and trenches and complicating logistics for the forward positions of Moscow's troops.

It comes amid reports that hundreds of Russian troops were able to enter the key city of Pokrovsk in the Donetsk region over the weekend.

It follows more than a year of operations in the area, where fighting is "highly dynamic and intense", according to the Ukrainian military.

Much of Russian fighting has centred around Donetsk, which forms part of the wider Donbas region, particularly since Donald Trump returned to the White House and launched a push for peace.

Vladimir Putin told the US president he would freeze the front lines across Ukraine if Kyiv were to give up the remaining 12 per cent of the strategic Donbas region.

Volodymyr Zelensky, the Ukrainian president, rejected Putin's demands, claiming the region would be used to launch further attacks.

Mr Zelensky said in his late Sunday address that the situation in Pokrovsk was "difficult" and success in the city - a key logistics chokepoint - was "critically important".

For the Kremlin, victory here would boost momentum at a time when Russia is said to be making slow but steady gains across the front line, and could open up a direct route into the heart of the Donbas.

Earlier this month, Valery Gerasimov, Russia's top military general, said that 31 Ukrainian battalions had been encircled by Russian forces in Pokrovsk, which were rejected by Russian military bloggers and Ukrainian sources.

Gerasimov was accused of lying about Russia's progress in the region in order to please Putin.