Turkish President Recep Tayyip Erdogan on Tuesday called for a "dignified way out" of the seven-month crisis sparked by Russia's invasion of Ukraine.

Erdogan has been using his good working relations with both Moscow and Kyiv to try and find a diplomatic solution to the war.

He spoke to Ukrainian President Volodymyr Zelensky by phone moments before addressing the opening session of the United Nations General Assembly with an urgent appeal for peace.

"Together, we need to find a reasonably practical diplomatic solution that will give both sides a dignified way out of the crisis," Erdogan told the United Nations.

He said a lasting peace must be based on protecting Ukraine's territorial integrity.

"We will continue to increase our efforts to end the war that has flared up again in recent days on the basis of Ukraine's territorial integrity and independence.

"I invite international organizations and all countries to give sincere support to Turkey's efforts."

Erdogan delivered his address hours after four Moscow-held regions of Ukraine announced plans to vote in the coming days on annexation by Russia.

NATO member Turkey never recognized the Kremlin's annexation of Ukraine's Crimea peninsula in 2014.