Just over half of Finns polled, 51 percent, said they are against Finland joining Nato in a fresh survey. Supporters of the conservative National Coalition Party (NCP) tend to back Nato membership while most leftists oppose joining.
The survey was published on Friday by three newspapers: Maaseudun Tulevaisuus, a rural paper with traditional ties to the Centre Party, the NCP-owned Verkkouutiset, and the main Swedish-language daily, Hufvudstadsbladet.
However only about a quarter (26 percent) of those surveyed stated an opinion on Nato membership. As the poll covered just over 1,100 people, the support results are based on the views of fewer than 300 people.
According to the poll, the strongest opposition was among backers of the Left Alliance, with 69 percent saying no to Finnish membership.
The most positive were supporters of the NCP, with 57 percent saying Finland should join the western military alliance. In general, Nato support was highest among those respondents with higher incomes and education levels as well as those who described themselves as politically right-leaning.
Finland joined Nato's Partnership for Peace in 1994, a year before joining the EU. In 2004 Finland and neighbouring Sweden stepped up cooperation with Nato, joining its Enhanced Opportunities Programme.
More uncertainty worldwide
Mika Aaltola, Global Security Programme Director at the Finnish Institute of International Affairs, says the results indicate that trends in Finland are in line with those elsewhere.
"Opposition to Nato has declined in recent years while the number of people who are unsure of their stance has increased," he said.
"Nothing dramatic has happened. Twenty-six percent giving a position is a bit more than I expected but not a major change."
The survey was carried out by pollster Kantar TNS, which questioned 1,106 people aged 15-74 in early June.
The newspapers say that those who responded were Finns. The agency estimates the margin of error at three percentage points.
In a poll taken nearly one year ago, one third of Finns surveyed said they would support Nato membership if President Sauli Niinistö endorsed it.