Published: Aug 24, 2011 4:56 PM EDT

STOCKHOLM (AP) - A new book claims IKEA founder Ingvar Kamprad's youthful ties with Nazi groups extended beyond what he has admitted, saying Sweden's intelligence agency even set up a file on him.
    
Respected Swedish author Elisabeth Asbrink's "And in Wienerwald the Trees Remain" says a 17-year-old Kamprad joined the Swedish Nazi party in 1943, prompting the security police to set up a file on him. It claims Kamprad's contacts with the Nazi world continued until the 1950s.
    
Kamprad has previously admitted sympathizing with fascist Per Engdahl and attending Nazi meetings in 1945-48.
    
His spokesman Per Heggenes on Wednesday reiterated that Kamprad sees his Nazi involvement as the "biggest mistake" of his life, but wouldn't comment on specifics.

(Copyright 2011 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.)