Support for NATO membership used to be steady at 20-30 percent but has soared in Finland, as well as neighbouring Sweden -- both historically militarily non-aligned -- in recent months.

Around 76 percent of Finns now want the country to join NATO, up from 60 percent in March, according to the poll commissioned by broadcaster YLE and conducted by research firm Taloustutkimus.

The survey also showed a majority in favour no matter the party alignment.

A separate poll last week showed most lawmakers in favour of joining, with 121 of the 200 MPs in favour and only 10 opposed.

Finland and Sweden have inched closer to the alliance, and are mulling a possible joint bid to better protect themselves from their neighbour, Russia.

There is widespread support for welcoming the countries into NATO, according to the alliance, but their membership needs to be ratified by the parliaments of all 30 current member states.

Only full members of NATO formally enjoy the protection of collective defence under Article 5 of the alliance's charter, which states that an attack on one member is considered an attack on all.

Finnish President Sauli Niinisto is due to announce his personal stance on a bid for NATO membership on May 12.

Many analysts speculate the countries will decide soon on any application so that they can be submitted before a NATO summit in June.