Speaking ahead of talks with NATO members including Turkey in Berlin, Pekka Haavisto said he was "confident that in the end we will find a solution and Finland (and) Sweden will become members of NATO".

Referring to a phonecall initiated by Finland's president to his counterpart in Russia, Vladimir Putin, the minister said it was "very important that we communicate with our neighbour" even if "we don't ask any permission for our political steps".

Moscow's February 24 invasion of Ukraine has swung political and public opinion in Finland and neighbouring Sweden in favour of NATO membership as a deterrent against Russian aggression.

Both countries have long cooperated with the Western military alliance and are expected to be able to join it quickly.

Underlining the tense situation, the minister stressed that it was critical for as many NATO members as possible to "announce clear support" for Finland from when it files its application to its final accession.