Shareholders of defunct German chemical giant IG Farben are asking Swiss bank UBS to pay €1.8 billion ($2.24 billion) in compensation for a 1967 takeover of a Swiss IG Farben subsidiary. Until 1940, Interhandel was owned by IG Farben, which manufactured the gas that killed Nazi concentration camp prisoners. Interhandel apparently became an independent company thereafter, but the U.S. government still confiscated its assets after the war. In 1965, Interhandel received about 500 million Swiss francs ($400 million, €320.5 million) from the U.S. government in compensation. The shareholders are now asking UBS for that money plus interest, claiming that new documents prove Interhandel still belonged to IG Farben at the time. Should the bank fail to respond by a Jan. 9 deadline, the shareholders plan to file a civil lawsuit in the U.S., according to their lawyer, Ed Fagan. A UBS spokesman on Monday denied the claims. Defunct since the end of World War II, IG Farben declared insolvency in November but its shares are still traded on the stock market.