Facts may have been concealed from KPMG auditors prior to their approving the accounts of Belgian voice recognition company Lernout & Hausie.
L&H has already admitted it will have to restate financial results for 1998, 1999 and the first half of 2000, as the SEC investigates allegations that Korean sales for the firm involved companies that denied they were customers.
KPMG said that the clean opinion issued in its audit report for 1998 and 1999 "could no longer be relied upon," according to the Financial Times.
The possibilty of concealment was revealed as former co-managing directors Pol Hauspie and Nico Willaert, and former president and CEO Gaston Bastiaens resigned from the board. Head of the Korean operation, Joo Chul (John) Seo, has been suspended.