Carlos Ghosn, chairman of the alliance between Nissan Motor Co., Renault SA and Mitsubishi Motors Corp., was arrested Monday over the alleged underreporting of his income and misuse of company funds, in an unprecedented scandal that sent shock waves through one of the world's top automaker groups.

Ghosn, 64, is expected to be relieved of his post Thursday at a meeting of the company's board of directors, Nissan CEO Hiroto Saikawa told a news conference later in the evening, adding that Ghosn's long reign had negatively impacted the firm's governance.

The carmaker said it had initiated an internal investigation after a report by a whistleblower revealed misconduct by Ghosn and Nissan Representative Director Greg Kelly, alleging that the two executives had conspired to underreport Ghosn's salary for a number of years.