Machines built by computer giant IBM helped the Nazi regime commit mass murder more efficiently, Gypsy groups have alleged.
IBM insists its machines were used without its connivance
A Swiss court has cleared the way for a lawsuit against the firm, asking for compensation for its wartime role.
IBM had an office in Geneva during the war, which the lawsuit alleges was used for trading with the Nazis.
The firm insists that it had no role in the Holocaust, and that its German unit was taken over before the war.
This was how IBM punch-card machines came to be used by the Holocaust bureaucracy, the company says.
Call for compensation
The case is one of many lawsuits launched by groups representing Jewish, Gypsy and other victims of the Holocaust.
Most actions so far have been based in the US, and have targeted German companies such as DaimlerChrysler, Volkswagen and Siemens, which can be shown to have profited from Nazi-era slave labour.
Some German companies have contributed to funds created to compensate victims and their families.
The IBM case could be more difficult, since the plaintiffs will have to demonstrate some knowledge on the part of the US firm that its machines were being put to immoral use.
IBM has, however, already paid into a German Government-led Holocaust fund.
A US lawsuit against the company was dropped in 2001.