Vladimir Putin met with UN Secretary-General Antonio Guterres on Tuesday in Moscow amid reports of the Kremlin chief's failing health.
It comes as Putin fuelled more speculation he's battling Parkinson's or another serious illness after he appeared "unsteady and distracted" at an Easter service over the weekend.
The Russian President has faced concerns about his physical and mental health since launching his invasion of Ukraine in February.
Experts have suggested a number of theories ranging from cancer and Parkinson's to steroid use and psychosis or a personality disorder.
New footage of Putin, 69, looking shaky and anxious at Moscow's Christ the Saviour Cathedral has further stoked the rumours.
On Friday, Putin was seen gripping the table, slouching and repeatedly tapping his foot - prompting rumours that he has Parkinson's.
The "bloated" Russian President looked "feeble and barely able to hold himself upright" as he gave orders in relation to the invasion of Mariupol.
He looked distracted and in pain as he told Sergei Shoigu to obstruct the Azovstal steelworks “so that not even a fly can escape”.
During today's meeting, Putin and Mr Guterres sat at opposite ends of a long white table - putting a considerable amount of distance between them.
Mr Guterres said they discussed ways to provide humanitarian assistance and evacuation of civilians from conflict zones, specifically Mariupol.
A UN spokesperson added: "The President agreed, in principle, to the involvement of the United Nations and the International Committee for the Red Cross in the evacuation of civilians from the Azovstal plant in Mariupol.
"Follow-on discussions will be had with the United Nations Office for the Coordination of Humanitarian Affairs and the Russian Defence Ministry."
Mr Guterres also Russia's Foreign Minister Sergey Lavrov about finding ways to come to a ceasefire.
He later told reporters it was "clear that there are two different positions on what is happening in Ukraine".
Later this week, Mr Guterres will go to Kyiv to Ukraine's President Volodymyr Zelensky.
It comes after the Ukrainian president criticised Mr Guterres for visiting Russia first.
Over the weekend, President Volodymr Zelensky told reporters it was "simply wrong" and "there is no justice and no logic in this order".
He said: "The war is in Ukraine, there are no bodies in the streets of Moscow.
"It would be logical to go first to Ukraine, to see the people there, the consequences of the occupation."
