The far-Right Sweden Democrats party has become the most popular in Sweden in a historic poll which marks the failure of long-term efforts by the traditional parties to freeze them out.

According to a poll published on Friday in the Aftonbladet newspaper, the populist party now has the support of 24 percent of voters, compared to just 22.2 percent for the Social Democrats, the lead party in the country's current coalition government.

"I'm not surprised. I've long argued we would be the biggest party sooner or later," party leader Jimmie Åkesson told the Aftonbladet newspaper.

"We've been talking constructively over gang criminality, escalating insecurity, and a migration policy that doesn't work for so many years."

Mr Åkesson has over the past 14 years transformed his party from a fringe white-power group by ruthlessly casting out its more extreme elements and claiming to uphold a zero-tolerance policy towards racism.

The poll, by the Swedish opinion research company Demoskop, marks the first time the party has been the largest party in any of the five opinion polls carried out on behalf of Sweden's mainstream newspapers and broadcasters.

The Social Democrats have been the biggest party in every election in Sweden since 1914, with the party building the country's generous welfare society over more than 40 years of unbroken rule from 1932 to 1976.