Sveriges Television journalist Elisabeth Åsbrink's book "Och i Wienervald" (literally: And in Wienervald) furthermore reveals that Kamprad was active in recruiting to Sweden's main war-time Nazi movement the National Socialist Workers' Party (Svensk Socialistisk Samling - SSS).
The book also details how the 17-year-old Ingvar Kamprad's movements were of sufficient interest to the Swedish security police in 1943 that his involvement was mapped in a security police file, leading to further questions about his links to the Nazis.
Åsbrink claims in her book that the predecessor to the Security Service (Säpo), Allmänna Säkerhetstjänsten ('Public Security Service'), steamed open young Ingvar Kamprad's letters and were thus able to establish his role in recruiting new members.
"It is a little odd that Ingvar Kamprad has not himself come out with this information. He has said that he wants to tell, and to say sorry," Elisabeth Åsbrink told SVT's Aktuellt news programme on Tuesday.
Åsbrink's book establishes that Kamprad's links to the SSS and far-right leader Per Engdahl continued long after the end of the war, and after the horrors of Adolf Hitler's regime and the Holocaust became known.
Kamprad was, for example, present at Per Engdahl's wedding in the 1950s, writing a letter at the time in which he expressed his pride to be part of the 'nysvenska' circles", referring to the nationalist movement founded by Engdahl in the late 1930s.
A spokesperson for the Ikea founder said on Wednesday that Kamprad was unaware that Swedish security services had files detailing the time he was active in the Nazi movement.
“But it's not that strange, that was Säpo's job to keep tabs on people on the right and left side,” Kamprad spokesperson Per Heggenes told the TT news agency on Wednesday.
“It confirms only one thing – that Ingvar time after time has told about the biggest mistake of his life and apologised to all involved 20 years ago.”
According to Heggenes, Kamprad hadn't seen the SVT report himself.
“But it's clear he hopes he can put this behind him. It's not fun to be reminded of it again and again – when he's been open from the beginning about it and apologised."
Heggenes doubted that the new details would have a negative impact on Ikea, however.
“It doesn't affect its image in any way. Everyone who knows Ikea knows that it's a multicultural company which practices a multicultural strategy,” he told TT.