Tutu expressed his disappointment in Oxfam on Thursday, after allegations of immorality and possible criminality involving humanitarian workers linked to the charity surfaced on Tuesday, according to a statement.
"He is also saddened by the impact of the allegations on the many thousands of good people who have supported Oxfam's righteous work," the statement read.
The scandal has also led Oxfam's chief executive Mark Goldring to resign just hours after his deputy, over a scandal involving aid workers' use of hookers in Haiti, following the devastating earthquake in 2010, AFP reported.
According to the report, a survey of 120 staff across three countries found between 11 and 14% witnessed or experienced sexual assault. Seven percent of staff in South Sudan witnessed or experienced rape or attempted rape involving colleagues.