UN chief demands 'peace' in Ukraine at Russia-hosted BRICS summit

United Nations leader Antonio Guterres has pleaded for a "just peace" in Ukraine, calling in a speech in front of Russian President Vladimir Putin for an end to more than two years of fighting.

Speaking on Thursday at a BRICS summit hosted by Putin in Russia's Kazan, Guterres also demanded an "immediate ceasefire" in Gaza, the release of hostages and an "immediate cessation of hostilities" in Lebanon.

"We need peace in Ukraine. A just peace in line with the UN Charter, international law and (UN) General Assembly resolution," Guterres told the summit.

The UN secretary general was in Russia for the first time since April 2022 and was due to hold talks on Ukraine with Putin later on Thursday.

Guterres has been critical of Moscow's offensive and illegal annexation of Ukrainian territory but there has been no halt in the fighting, now grinding through its third year.

He said it was essential to respect "the principles of sovereignty, territorial integrity and political independence of all states".

Putin, meanwhile, said Russia could not be defeated on the battlefield in Ukraine, warning of "illusionary" Western hopes.

Moscow's opponents "do not conceal their aim to deal our country a strategic defeat", he said.

"I will say directly that these are illusionary calculations, that can be made only by those who do not know Russia's history."

'Ask Pyongyang'

Guterres's spokesperson said the UN chief was willing to offer his mediation when Ukraine and Russia were ready and would use the meeting to reiterate his position on the conflict.

The UN secretary-general has condemned Moscow's military offensive and visited places in Ukraine where Russia's army has been accused of atrocities.

He also helped broker a deal that allowed Kiev to safely export grain from its ports through the Black Sea, the most significant diplomatic agreement between Russia and Ukraine amid the conflict.

But there has been little direct contact between the two countries since and Moscow has been advancing in eastern Ukraine for months.

Putin has demanded Kiev surrender territory as a precondition for a ceasefire.

Guterres and Putin will meet a day after the United States said it believed "thousands" of North Korean soldiers were being trained in Russia.

Putin has not yet commented on the reports.

Russia's Foreign Ministry spokesperson said on Wednesday people should "ask Pyongyang" about its troop movements, refusing to confirm or deny the allegations.

As the war in Ukraine dragged on towards its third anniversary, the Russian parliament approved on Thursday a budget that will see defence spending surge by almost 30 percent.