Delphi Corp., the nation's largest auto supplier, on Thursday said that an executive and a former executive have resigned because of accounting irregularities at the company, bringing to four the number of high-ranking employees who have left because of the errors.

According to the Associated Press (AP), Delphi, which is under federal investigation for its accounting, said it has accepted the resignations of treasurer Pam Geller and John Blahnik, former vice president of treasury, mergers and acquisitions - spokeswoman Claudia Baucus confirmed the resignations were related to the accounting investigation.

AP said John Arle, 57, has been named vice president and treasurer, effective immediately, and will report to John Sheehan, Delphi's acting chief financial officer - Arle was previously vice president of Delphi's corporate audit services.

Derek Kolano, 33, will serve as acting director of Delphi's corporate audit services until Arle's successor is named, AP added.

Delphi reportedly said it's on track to finish its internal investigation and release restated financial reports by June 30.

According to AP, in a Thursday filing with the US Securities and Exchange Commission, Delphi said that from the time of its 1999 spin-off from General Motors until the end of the third quarter of 2004, it wasn't accurately disclosing the amount of sales of European accounts receivable and factors relating to sources of short-term liquidity.