Chief executive officer Datuk Bridget Lai and chief operating officer Shim Kon Teck had each been asked to answer a set of questions as part of a probe on corporate governance issues.
They had replied to these on Monday, last week.
"The (bank's) lawyers and accountants are still going through many, many documents," a source told Business Times.
The source could not say how much more time the professionals required to complete their assessment, but indicated that it may take a week more.
Once this is done, the board is expected to act on the lawyers' legal advice.
Analysts have stressed that it is important for the bank to complete its probe as soon as possible to remove any uncertainties that investors may have about the bank's leadership.
Lai has been on leave since December 15 to facilitate the probe.
