Defence Secretary William Wallace warned it was ‘inconceivable’ that the UK would not ‘support’ the Scandinavian states, which have been threatened by Moscow.
Finland and its neighbour Sweden have expressed a desire to join the military pact since Putin launched his savage invasion of Ukraine in February.
Reuters reported this week that Helsinki will formally announce its bid to join on May 12 with Sweden following suit days later.
Mr Wallace said: ‘Do I think if Finland didn’t join Nato Britain wouldn’t come along to help? No. Britain will always be here in the Nordics, to be part of you, to help you, to support you.
‘It is inconceivable that Britain would not come to the support of Finland, or Sweden, if it was ever attacked, without any big formal agreement. We are European countries who share the same values, who have deep, long histories.
‘A significant number of the British population seem to be descended from Vikings anyhow, so we have that cultural link.
‘I cannot conceive a time when we wouldn’t come to support Finland and Sweden no matter where they were with the Nato debate or where they are with agreements.’