Finnish President Sauli Niinisto has called Russian President Vladimir Putin; during the conversation, he insisted on declaring a ceasefire in Ukraine and brought up the problem of safety and security of Ukrainian nuclear facilities, the Finnish presidential office said in a statement on Friday.

"In a conversation focused exclusively on the war in Ukraine, President Niinistö emphasized the deepening catastrophe and deep human suffering in Ukraine, which also has a strong influence on public opinion in the West," the statement says.

President Niinisto underscored the need to achieve an immediate ceasefire and to ensure a safe evacuation of civilians through humanitarian corridors.

Niinisto also brought up the subject of "safety and security of the nuclear energy facilities in Ukraine," it said.

The Finnish leader also informed his Russian counterpart of a conversation he had previously had with Ukrainian President Volodymyr Zelensky, who once again offered to hold direct talks with Putin.