The Ukrainian armed forces confirmed on Thursday that Russian forces have broken through through to the village of Ocheretyne in Donetsk after several days of fighting.
"As far as Ocheretyne is concerned, the enemy has broken through and has established itself in this village," the spokesman of the Khortytsya army group fighting in this section, Nazar Voloshyn, told the Interfax-Ukraine news agency.
However, he added that the corresponding part of the town was being shelled by Ukrainian artillery, and the Ukrainian troops were trying to push the Russians back.
"With this goal in mind, additional forces and resources were brought in from the reserve," he said.
Currrently, the fiercest battles are raging in the front sections towards Pokrovsk and Kurakhove, he said, and while Moscow has achieved tactical successes, it has not yet gained an operational advantage.
His comments came after the Ukrainian General Staff reported fierce fighting and a total of 121 battles over the past 24 hours.
They said that they had repelled Russian attacks near Ocheretyne and that there had been fierce and intense fighting in previous days, particularly in the Donetsk region.
Meanwhile Ukrainian military observers said Russian forces had broken through to Ocheretyne almost two weeks ago and have since identified further Russian territorial gains.
Moscow is still trying to take over the whole of the eastern Ukrainian region of Donetsk.
Parts of Donetsk and Luhansk have been under the control of Moscow-backed separatists since the spring of 2014.
They are among four Ukrainian regions claimed by Moscow since it launched its full-scale invasion in February 2022.
Moscow's forces annexed the Crimea peninsula illegally in 2014, then Russia claimed the Ukrainian regions of Donetsk, Luhansk, Zaporizhzhya and Kherson as its territory after its latest incursion.
Amid calls for an end to the conflict, Moscow insists on its claimed right to rule over its neighbour and argues that, at most, the future of western Ukraine is unclear.
However, Kiev is calling for the withdrawal of Russian troops, reconstruction and reparations, and the prosecution of war criminals in a peace plan presented by Ukrainian President Volodymyr Zelensky to the United Nations in 2022.
Ukraine wants the perpetrators of alleged war crimes in Ukraine to be brought to justice and also seeks security and territorial guarantees.
In attempts to end the conflict, Switzerland earlier sent out official invitations to more than 160 delegations ahead of its Ukraine peace conference - though Moscow was not among the invitees.
The peace talks are scheduled to take place on June 15-16, with global leaders expected to atend.
Switzerland is organizing the meeting at Kiev's request, with the aim of developing a pathway to a lasting peace. Russia has not been invited, as Moscow has said several times it would not participate, the Swiss Foreign Ministry said.
The conference aims to bring together countries that have a shared understanding of the steps towards a solution, Ukrainian Foreign Minister Dmytro Kuleba told Foreign Policy, a US magazine.
That would be followed by communication with Russia, and Moscow could be involved in negotiations, as the war cannot be ended without the participation of both sides, said Kuleba.
The Kremlin dismissed this approach. "How can we talk about a serious conference with serious results without Russia's participation?" spokesman Dmitry Peskov said in Moscow.
Russia's stance carries weight because China is calling for a peace conference that is acceptable to both Russia and Ukraine. It is unclear whether China will join the Swiss event.
Switzerland's aim, however, is precisely to generate understanding for Ukraine's position among states that have so far backed Russia or taken a neutral stance such as China, India, Brazil and South Africa.