"We want a solid platform to work for important European questions," SDU chair Gustav Kasselström told The Local by phone from Vienna, home of new partner the Freedom Party of Austria.
He said that the main common points would be EU criticism, immigration criticism, and how to strengthen national identities. The new cooperation would not extend to national level.
"Exactly which positions they adopt in France, or Austria, or Flanders, that's their business, and they won't interfere in our politics," Kasselstrand said.
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SDU announced its plan to seek European partners already last summer, while political commentators at home, including EU Affairs Minister Birgitta Ohlsson, have asked the Sweden Democrat party to come clean about whom it intends to cooperate with on EU level.
Maria Demker, political scientist at Gothenburg University, noted that SDU had chosen partners that were further to the right than for example the immigration-critical Dansk Folkeparti in Denmark.
"The youth wings that SDU will cooperate with belong to the group within the party family that has a significantly more ultra-nationalist or a very strong nationalist line, compared to parties for example such as Dansk Folkeparti," she told Sveriges Radio.
She said the different gradations within the Sweden Democrats were also visible on European level.
"That conflict exists within the Sweden Democrats, but also in Europe. So this is a way of taking a stance in that conflict."