Ingvar Kamprad, who died this past weekend at the age of 91, was best known as the founder of the Ikea furniture chain.

But Mr Kamprad, who at the time of his death was one of the richest men in Europe, became known for something far more sinister in the latter part of his life – links to far-right parties in Sweden during the Second World War.

Mr Kamprad founded his company in 1943. Ikea is an acronym made up of his name (Ingvar Kamprad), the family farm he was born at (Elmtaryd) and the nearby village in which he was raised, Agunnaryd.

He went on to build it into a global brand – and at the time of his death, he was worth over $57 billion (£40.5 billion).

But when Swedish far-right politician Per Engdahl died in 1994, his personal letters revealed that Mr Kamprad joined the Engdahl’s New Swedish Movement in the same year he founded Ikea, working as a fundraiser and recruiter for the group until mid-1945.

His friendship with Engdahl continued into the mid-1950s.

When the letters went public, Mr Kamprad issued an apology to Ikea's staff – then numbering over 25,000 – in which he described his wartime connection to fascism as “the greatest mistake of my life”.

However, in 2011, a book by Elisabeth Asbrink, a Swedish journalist, charged that Mr Kamprad’s far-right sympathies had gone even further.

In addition to his involvement in the New Swedish Movement, Ms Asbrink accused Mr Kamprad of having also been a member of the Svensk Socialistisk Samling (SSS), neutral Sweden’s own version of the Nazi party.

Ms Asbrink’s books also alleged Sweden’s security services opened a book of records on Ingvar Kamprad in 1943, titled “Nazi”, which included his SSS membership number – 4013 – and intercepted letters in which the 17-year old wrote that he “misses no opportunity to work for the movement”.

Mr Kamprad was well known for his parsimony, with reports that he reused tea bags and would pocket salt and pepper sachets at restaurants. He wrote a number of books regarding his belief about how a company should be run.

In his own book, Testament of a Furniture Dealer, Mr Kamprad said: “It is not only for cost reasons that we avoid the luxury hotels. We don't need flashy cars, impressive titles, uniforms or other status symbols. We rely on our strength and our will.”

Although he lived in Switzerland for almost forty years, Mr Kamprad returned to Sweden in 2014.

He died in his sleep on Saturday January 27.