South Korea's financial watchdog is stepping up its probe into Daewoo Engineering & Construction Co.'s alleged accounting fraud and may expand its inspection into its largest shareholder, the Korea Development Bank (KDB), depending on the outcomes, industry sources said Friday. Daewoo Engineering has been under an audit review by the Financial Supervisory Service (FSS) on accounting fraud charges based on a tip-off it received last year. The builder was originally affiliated with the now-defunct conglomerate Daewoo Group, which went belly-up following the Asian financial crisis in the late 1990s. The FSS did not rule out the possibility of expanding the probe further into a special investigation once the audit review is completed