April elections in Finland could see the rise of yet another Northern European anti-immigrant, nationalist rightwing party that flatly rejects the far-right label while using populist rhetoric.

The True Finns is the latest such party to show signs of gaining mainstream traction.

Opinion polls suggest its showing in the April 17 parliamentary election could leap from its 4.1 percent score in the 2007 election right up to 20 percent.

The True Finns, Sweden Democrats (SD), the Danish People's Party (DPP) and Norway's Progress Party (FrP) are all already represented in their respective national parliaments.

There, they emphasise the importance and of "lifestyle politics such as abortion, gay marriages, gender education, immigration," says Swedish political scientist Anders Hellstroem.

"They are authoritarian, pro-family, want law and order, and are opposed to immigration. In that sense, they are all far-right," he tells AFP.

At the same time, however, since they are all represented in parliament, "all are established. They are part of the mainstream," he says.

The far-right label, which signals extremism, is therefore not completely accurate.

In Finland, for instance, the True Finns are far from having a monopoly on anti-immigration rhetoric, says writer and political analyst Jussi Foerbom: better-established parties having long "used pretty merciless and harsh language in the discussion of immigration."

The party has however by far been the most successful in transforming the issue into popular support.

All the Nordic populist parties tend to oppose high taxation levels, while still backing the social welfare models associated with their countries.

They are also trying to gain respectability.

Sweden's SD, which with its neo-Nazi roots has the most dubious past of the Nordic parties, has for instance purged the most extreme elements from its midst.

A True Finns city councillor was convicted for blog comments linking Islam to paedophilia and saying Somalis were predisposed to mugging people and living on the dole.

But Raimo Vistbacka, a party founding member, told AFP his behavior could be attributed to the fact that "every party has these young radicals."

"They mellow out as they get more experience," he said.

When Sweden's SD entered parliament for the first time last September after elections that handed Prime Minister Fredrik Reinfeldt's centre-right coalition minority rule, all the other parties pledged to isolate it.

The party has nevertheless been able to play kingmaker in a line of important parliamentary votes, handing the win to the government or the left-leaning opposition as it sees fit.

And the True Finns party, which has been represented in parliament since 1996, could very likely become the first of the Nordic populist parties to actually make it into government.

Denmark's DPP has also secured widespread mainstream acceptance.

In its role as key ally to the centre-right coalition in power since 2001, it has helped shape government policies and push Danish immigration policies to become among the most restrictive in Europe.

The party's head Pia Kjaersgaard has said she sees the party as "rather close to French Gaullism".

The DPP has been an ally to the minority government for 10 years and is Denmark's third largest party.

Danish Prime Minister Lars Loekke Rasmussen has said it represents "a fringe of the electorate we can't ignore."

It has "made a lot of efforts not to be affiliated with the SD (in Sweden)," Swedish political scientist Hellstroem says, stressing however that "SD is no further right than DPP."

The DPP is now considered a possible coalition partner after general elections in Denmark later this year.

In Norway too, where the FrP has long been the second-largest party, there are signs it could for the first time be allowed into a government coalition after the next vote in 2013.

Such high acceptance level might seem far away for the SD, as its roots are much more extreme.

Norwegian political scientist Frank Aarebrot at the University of Bergen argues however that the Swedish party does not really differ much from the other populist parties in the region.

"But they are at different stages in their development," he says, pointing out that "FrP, when it was as young as (the) SD, was at least as isolated."