The war in Ukraine will continue until "Russia decides to end it," the United Nations Secretary-General António Guterres told CNN on Wednesday.

“The war will not end with meetings,” he told CNN's Anderson Cooper during a wide-ranging interview. “The war will end when the Russian Federation decides to end it and when there is – after a ceasefire – a possibility of a serious political agreement. We can have all the meetings but that is not what will end the war.”

On Tuesday, Guterres traveled to Moscow for a one-on-one meeting with Russian President Vladimir Putin to discuss “proposals for humanitarian assistance and the evacuation of civilians” from conflict zones, namely the besieged city of Mariupol, according to a UN readout of the discussion.

As a result, Putin agreed “in principle” to allow the UN and the International Committee for the Red Cross to assist in the evacuation of citizens from the Azovstal plant in Mariupol, the last bastion of Ukrainian defense in the city.

Asked what role the UN intended to play in the investigations of war crimes allegedly carried out by Russian forces in the town of Bucha on the outskirts of Kyiv, Guterres reiterated his calls for an “independent investigation.”

The Kremlin has denied any involvement in the mass killings of civilians in Ukraine while reiterating baseless claims that images of bodies on the streets of Bucha are “fake.”

Evidence of mass graves in the towns of Bucha and Borodianka has continued to emerge since early April, following the withdrawal of Russian forces from the Kyiv region.