Russian President Vladimir Putin met with visiting United Nations (UN) Secretary-General Antonio Guterres in the Kremlin on Tuesday to discuss the situation in Ukraine.

Putin told Guterres that the Ukrainian issue arose after the 2014 "unconstitutional coup" in Kiev and people in Donbass remained under blockade and military pressure even after the Minsk agreements on a peaceful settlement were reached.

According to Putin, the Donbass "republics" have the right to declare their sovereignty and Russia has the right to recognize their independence and provide them with military assistance in full accordance with the UN Charter.

"Despite the ongoing military operation, we still hope that we will be able to reach agreements on the diplomatic track. We are negotiating and we do not refuse them," he said.

Guterres proposed creating a contact group where the UN, Russia and Ukraine can discuss the situation together so that the humanitarian corridors are truly effective.

He said that to resolve the situation in Ukraine's Mariupol, the UN is ready to fully mobilize its logistical capabilities and human resources, working together with the International Committee of the Red Cross (ICRC) as well as the Russian and Ukrainian armed forces.

Guterres also said that the UN is ready in two or three days, together with the ICRC, to assess the situation at the Azovstal plant in order to evacuate civilians from there.

In response, Putin denied reports that Russian humanitarian corridors are not working and stressed that 130,000 to 140,000 people have left Mariupol with the assistance of Russia and they are free to go anywhere.

Putin also offered an opportunity to UN and ICRC representatives to have a look at how Russia treats Ukrainian war prisoners.

Before his trip to Moscow, Guterres met with Turkish President Recep Tayyip Erdogan on Monday in the capital Ankara. The UN chief will travel to Ukraine following talks with Putin.