Russia is trying to push Ukrainian forces from its western Kursk region with tens of thousands of soldiers, Ukraine’s president says, aiming to retake territory it has lost since August while its offensive in eastern Ukraine grinds on.

In a post on Telegram on Monday, President Volodymyr Zelenskyy said Ukraine’s soldiers were fighting against nearly “50,000 enemy troops” in Kursk.

Zelenskyy said Ukraine would “considerably strengthen” its positions on the Pokrovsk and Kurakhove fronts in the east, where the most active fighting is occurring.

In August, Ukraine launched a surprise incursion into Kursk, seizing settlements in its first operation in Russian territory since Moscow launched its invasion in February 2022.

Russia, however, has continued its slow but steady advance across much of eastern Ukraine, which it is capturing village by village in a bid to seize the entire industrialised Donbas region.

Zelenskyy’s comments come a day after The New York Times reported that Moscow had assembled a force of 50,000 soldiers, including North Korean soldiers, in the Russian region bordering Ukraine.

Western countries, South Korea and Ukraine have all said North Korea has sent soldiers to Russia.

Russia has neither confirmed nor denied the presence of North Korean soldiers on its territory.

On Saturday, Russian President Vladimir Putin signed into law a treaty on Moscow’s strategic partnership with Pyongyang, including a mutual defence provision.

Russian attacks on Monday killed two in Ukraine’s central-east Dnipropetrovsk region and injured at least 19, with more people likely trapped under the rubble, officials said.

Shelling by artillery killed two people in Nikopol and injured five more, regional governor Serhiy Lysak said on the Telegram messenger platform.

A medical facility, a cafe and shops were damaged, he added.

Separately, at least 14 people were wounded after Moscow’s troops launched a missile at a residential building in Kryvyi Rih, central Ukraine, in the morning, according to Lysak.

Rescuers were looking for a woman with three children likely trapped under the rubble, he added. A 10-year-old girl and an 11-year-old boy were among the injured.

A Ukrainian military spokesperson also told the Reuters news agency on Monday that Russian infantry groups could launch ground assaults on the neighbouring Zaporizhia region in a matter of days.

The spokesperson said the attacks could put more pressure on Kyiv’s forces, which are already overstretched.

“[The assaults] could begin in the near future. We’re not even talking about weeks. We’re expecting it to happen any day,” Vladyslav Voloshyn told Reuters.

Also on Monday, Russian attacks damaged a dam near the front line in the eastern Donetsk region of Ukraine, its governor said, warning that nearby villages could be threatened by rising water levels.

Moscow’s army is rapidly advancing in the Donetsk region and is closing in on the town of Kurakhove, which lies next to the reservoir and had a pre-war population of about 18,000 people.

“The Russians damaged the dam of the reservoir of Kurakhove. This strike potentially threatens residents of settlements on the Vovcha River, both in Donetsk and Dnipro regions,” Governor Vadym Filashkin said.

Kremlin denies Putin-Trump conversation

On Monday, Kremlin spokesperson Dmitry Peskov denied Putin had spoken to US President-elect Donald Trump on the Ukraine war despite reports that the leaders had spoken.

“This is the most obvious example of the quality of the information that is being published now, sometimes even in fairly reputable publications,” Peskov said, adding that there were “no concrete plans yet” for Putin to contact Trump.

During his campaign to win the White House, Trump said he could end the Russia-Ukraine war within 24 hours if elected without elaborating.

Separately, the Kremlin said it sensed that European powers were nervous about Trump’s presidency and it was too early to speak to European leaders about ending the conflict as they continue to supply Kyiv with weapons.

“No preparation is being carried out now [to speak to European leaders]. We have not received any signals,” Peskov said. “European leaders are continuing … to try to achieve a strategic defeat of Russia.”