The resignation comes at a time when Oxfam is battling to save its British government funding after a newspaper reported alleged sexual misconduct by its staff in Haiti during humanitarian relief operations.
Further, former head of safeguarding, Helen Evans, had revealed that teenage volunteers at UK shops had been abused and overseas staff had traded aid for sex.
Evans had said that the staff had been accused of rape and that sexual abuse by shop managers in UK stores against young volunteers was covered up, the Telegraph reported.
Her allegations emerged just hours after the resignation of Penny Lawrence.
Concerns have also been raised over Oxfam's use of public money.
Oxfam executives met with the International Development Secretary Penny Mordaunt on Monday evening in an attempt to assure the minister that the charity could be trusted with the
32m of public finding it receives.
"We recognise that we have some way to go to persuade her that we have the right moral leadership to be fully entrusted with public money," The Telegraph quoted Oxfam chair of trustees, Caroline Thomson. (ANI)