Sweden's top three parties are running almost level four months ahead of a general election, with the far-right and anti-immigration Sweden Democrats polling a record 20 percent, according to poll in daily Dagens Nyheter published Wednesday.

Support for the Sweden Democrats has surged since they first won seats in parliament in 2010, with the party on track to record its best ever election result after getting 13 percent in 2014.

A surge in asylum numbers in 2015, when Sweden took in 160,000 refugees, has heightened worries about a creaking welfare state and that crime is increasing, boosting the party, which wants to close Sweden's doors and crack down on gangs.

The ISPOS poll put the Sweden Democrats hot on the heels of the governing Social Democrats, who got 24 percent, and the biggest opposition party, the center-right Moderates, who scored 22 percent.

At the last election the center-left Social Democrats got 31 percent and the Moderates 23.3 percent.

The current government is a minority coalition of the Social Democrats and Greens led by Prime Minister Stefan Lofven. They are supported in parliament by the Left Party. Together, the parties polled 37 percent.

The Moderates, Center, Christian Democrats and Liberals cooperate and will fight the election as a group. They polled 39 percent.

Neither bloc can form a majority government without the Sweden Democrats and both have ruled out a deal with the party, which has its roots in the neo-Nazi fringe.

The poll suggests the Sweden Democrats are most popular among men (26 percent). Some are former Social Democrats voters attracted to the group's anti-immigration rhetoric.

The Nordic nation has registered some 400,000 asylum applications since 2012, one for every 25 inhabitants.

To contain the refugee influx, the minority center-left government has reestablished border controls and toughened conditions for granting asylum, residence permits and family reunification.

But some analysts warn the measures might not be enough for the government to win over voters.

"The Social Democrats have voters who are drawn to opposite sides. There are the traditional workers in smaller areas and the urban voters who appreciate cultural diversity," David Ahlin, who is responsible for the Ipsos poll, told Dagens Nyheter.

However, Ahlin said the Social Democrats' "success in keeping a wide coalition of voters together doesn't seem to be working any longer".

The survey interviewed 1,818 people through telephone and online.