Explainer: How humanitarian mission in earthquake-hit Haiti became a scandal
Here are some of the questions being asked about the Oxfam scandal:
Why was Oxfam operating in Haiti at the time of the scandal?
Oxfam UK was one of many charities responding to a massive earthquake which hit Haitian capital Port-au-Prince in 2010, killing 220,000 people, injuring 300,000 and leaving 1.5m homeless.
What were Oxfam staff accused of?
An internal investigation was launched into claims that some staff in Haiti invited prostitutes for sex parties at their villa.
What action was taken?
Oxfam's country director in Haiti, Roland van Hauwermeiren, and two other men in management resigned without disciplinary action in 2011. Four men were dismissed for gross misconduct. None of those accused was arrested or faced criminal charges.
What criminal charges could wrongdoers conceivably have faced?
Prostitution is illegal in Haiti and the age of consent is 18, raising the possibility of prosecution in the Caribbean nation. If any of the prostitutes involved was shown to be below the age of consent, there could potentially be a prosecution in the UK under the Sexual Offences Act 2003, which enables British citizens and residents who commit sexual offences against children overseas to be prosecuted at home.
Why were police not involved?
Oxfam said in a statement it had received legal advice that it was "extremely unlikely that reporting these incidents to the police would lead to any action being taken", given the chaotic conditions following the earthquake. The charity has also said that allegations that underage girls may have been involved were "not proven".
How did the scandal come to light?
Oxfam announced the launch of its investigation in August 2011, and publicised the outcome in September of that year. However, details of the investigation report did not become public until last week, when The Times published details of what it termed a "cover-up".
How did Oxfam react?
The charity released a statement saying that the actions of some aid workers had been "totally unacceptable, contrary to our values and the high standards we expect of our staff". After the Haiti investigation, it created a dedicated safeguarding team and a confidential 'whistleblowing' hotline.
The deputy chief executive of Oxfam GB Penny Lawrence resigned.
"I am deeply sad to announce that I have resigned as deputy chief executive of Oxfam GB," she said in a statement.
"Over the last few days we have become aware that concerns were raised about the behaviour of staff in Chad as well as Haiti that we failed to adequately act upon.
"It is now clear that these allegations - involving the use of prostitutes and which related to behaviour of both the Country Director and members of his team in Chad - were raised before he moved to Haiti.
"As programme director at the time, I am ashamed that this happened on my watch and I take full responsibility.
"I am desperately sorry for the harm and distress that this has caused to Oxfam's supporters, the wider development sector and most of all the vulnerable people who trusted us.
"It has been such a privilege to work for such an amazing organisation that has done and needs to continue to do such good in the world."
Is the problem confined to Oxfam?
It does not appear so. Former international development secretary Priti Patel has spoken of a "culture of denial" about sexual exploitation in the international charity sector stretching back decades. And the Charity Commission's director of investigations Michelle Russell said the watchdog received reports of 1,000 incidents a year involving "safeguarding" issues.