"If we are required to start the trial under these circumstances, the likely outcome would be acquittal," Prosecutor Daryl Mundis said, asking for three more days to persuade judges to allow him to call more witnesses.
In order to speed up the trial, judges have reduced the number of prosecution witnesses from 91 to 55.
Delic is charged with failure to prevent or punish acts of murder, rape and torture committed by men under his command.
His trial was supposed to start on Monday, but instead of reading an opening statement Mundis asked for more time to discuss the issue of witnesses with judges.