Finnish President Sauli Niinisto has told Vladimir Putin that the militarily non-aligned Nordic country that shares a long border with Russia "will decide to apply for NATO membership in the coming days".
Mr Niinisto's office said in a statement that he told the Russian president in a phone conversation how Finland's security environment had changed after Moscow's February 24 invasion of Ukraine.
It also pointed to Moscow's demands for Finland to refrain from seeking membership in the 30-member western military alliance.
"The discussion (with Putin) was straightforward and unambiguous and was held without exaggeration, said Mr Niinisto, Finland's president since 2012 and one of few western leaders who has held regular dialogue with Mr Putin over the past 10 years.
"Avoiding tensions was considered important."
He pointed out that he told Mr Putin at their first meeting in 2012 that "each independent nation would maximise its own security".
"That is still the case. By joining NATO, Finland will strengthen its own security and assume its responsibilities. It is not something away from anybody," Mr Niinisto said.
Watch: Finland's military strength explained.
He stressed that Finland, despite its likely membership of NATO, wants to continue to deal with Russia bilaterally in "practical issues generated by the border neighbourhood" and hopes to engage with Moscow "in a professional manner".
The phone call was conducted on Finland’s initiative, Mr Niinisto's office said.
However, the Russian President warned his Finnish counterpart relations between the two neighbours could be "negatively affected" if Finland follows through with plans to apply for NATO membership.
The Kremlin's press service said in a statement that Mr Putin told Sauli Niinisto that Finland's abandonment "of its traditional policy of military neutrality would be an error since there are no threats to Finland's security".
"Such a change in the country's foreign policy could negatively affect Russian-Finnish relations, which had been built in the spirit of good neighbourliness and partnership for many years, and were mutually beneficial," the statement added.
Watch: Why Finland wants to join NATO.
Finland shares an 830-mile border with Russia, the longest of any European Union member.
Mr Niinisto and Finnish Prime Minister Sanna Marin on Thursday jointly endorsed the country's NATO bid and recommended that the country "must apply for NATO membership without delay" to guarantee the nation’s security amid Russia’s invasion of Ukraine.
A formal announcement from Mr Niinisto and Ms Marin that Finland intends to apply for NATO membership is expected on Sunday, a day after the likely endorsement by Ms Marin's governing Social Democratic Party.
Neighbouring Sweden is set to decide on its NATO stance on Sunday in a meeting of the governing Social Democratic Party led by Prime Minister Magdalena Andersson.
US President Joe Biden held a joint call on Friday with Mr Niinisto and Ms Andersson during which, according to the White House, he "underscored his support for NATO's Open Door policy and for the right of Finland and Sweden to decide their own future, foreign policy and security arrangements".