Ukrainian President Volodymyr Zelenskyy has reiterated his demand that Russia swiftly present its peace memorandum, after speaking with his Turkish counterpart.

Zelenskyy spoke with Turkish President Recep Tayyip Erdogan on Friday over the phone, after Russia had proposed holding another round of direct talks with Ukraine in Istanbul, Turkey next Monday.

Zelenskyy posted on social media after the phone call that they both "share the view that this meeting cannot and should not be empty." He indicated that he wants to work with Turkey to urge Russia to present its memorandum.

He said that they also discussed the possibility of organizing a four-party meeting between the leaders of Ukraine, Russia, Turkey and the United States.

Russia proposed next Monday's meeting with Ukraine to discuss their peace memorandums.

Meanwhile, Kyiv says both sides need to examine each other's memorandum beforehand in order to make the meeting meaningful. Kyiv says that it has already handed over its document to Russia and has been urging Moscow to do the same.

Zelenskyy expressed strong criticism in a video address on Friday, by saying Russia is "concealing" its memorandum.