Businesses in Germany have only managed to raise DM3bn ($1.4bn) out of the total, which was agreed in a deal brokered by the German and American governments late last year.
Plans for US President Bill Clinton to sign the compensation agreement in Berlin next week are now in doubt after talks in Washington broke down over the key legal guarantees demanded by German companies to protect them from further US lawsuits.
The Remembrance, Responsibility and Future Foundation, as the fund is called, is intended to compensate surviving concentration camp prisoners and others from Central Europe who were forced to work for the Nazi war effort.
Although Germany has compensated the victims of war crimes, it has never provided for the estimated 12 million people put to work by Adolf Hitler's regime.
Contributors named
The German Government will match the DM5bn promised by industry, bringing the total to DM10bn ($4.63bn).
But the uncertainty over future legal action is hindering efforts to get firms to contribute.
In a bid to encourage other contributors, fund organisers have published a list of 2,000 supporting companies, including German industrial giants Siemens, Volkswagen and Daimler Chrysler which benefited from slave and forced labourers during World War II.
Double-page newspaper adverts appealed to firms not on the list to acknowledge their moral responsibility and join the fund.
The contributors are not necessarily firms who employed slave labour or were active in Germany at the time of the Nazi regime.
Ageing victims
The government has rejected an industry request that state-owned companies should contribute to the fund.
But there is a keen sense of time running, as the surviving victims are all now very old.
The German Government hopes to begin payments by the end of the year, a gesture which it sees as a final settlement of the country's Second World War liabilities.