CUACOS: UN Secretary-General Antonio Guterres said peace negotiations to end the conflict in Ukraine were "not possible at this moment," in an interview published by Spanish daily El Pais on Tuesday.
His statement came as the leaders of Russia and Ukraine called for victory during events commemorating the end of World War II.
"It is clear that the (two) parties are completely absorbed in this war" and "are convinced that they can win", the UN chief was quoted as saying by the newspaper.
Guterres said he hoped it was possible "in the future" to bring Russia and Ukraine to the negotiating table.
Russian President Vladimir Putin said on Tuesday at Moscow's Red Square Victory Day parade the world was at a "turning point" and claimed a "war" had been unleashed against Russia.
The day before, Ukrainian President Volodymyr Zelensky vowed that Russian forces would be vanquished "just as Nazism was defeated".
Chinese Foreign Minister Qin Gang is visiting Europe this week as China pushes to act as a mediator in the Ukraine conflict.
On Tuesday, Guterres received the Carlos V European Award, given to individuals or organisations that have contributed to the enhancement of Europe's cultural and historical values or to EU integration.
"Universal values, principles and ideas which unite us as the human family... have not been under so much threat since the creation of the United Nations," Guterres said.
"The Russian invasion of Ukraine... cause the country and its population suffering and massive destruction and add to the global economic disruption provoked by the Covid-19 pandemic.
"That's why we have to raise our voice and reaffirm our values. And above all, we need peace," added the 74-year-old former prime minister of Portugal.