Oxfam's chief executive has denied there was any cover-up after it was revealed some of its aid workers used prostitutes in Haiti in 2011.
Mark Goldring said the UK-based charity was ashamed of what it had got wrong but had taken action and been proactive about going public on the matter.
At the time, the charity only referred to it as "serious misconduct".
The Department for International Development, which gave Oxfam nearly £32m last year, is reviewing funding.
Mr Goldring told BBC Radio 4's Today programme the charity did "anything but" cover the incident up, adding: "We were very open with the public that we were ashamed of the behaviour of our staff. We still are."
However, he said a report released by the charity did not give details of the allegations.
The chief executive said: "With hindsight, I would much prefer that we had talked about sexual misconduct.
"But I don't think it was in anyone's best interest to be describing the details of the behaviour in a way that was actually going to draw extreme attention to it when what we wanted to do was get on and deliver an aid programme."
He added: "I am absolutely committed… to wipe out that kind of behaviour from Oxfam and rebuild that relationship of trust [with the public]."
Four staff members were dismissed over the revelations and three, including the country director for Haiti, were allowed to resign before the end of the charity's own investigation, it said.
The director was Roland Van Hauwermeiren, who according to the Times, used prostitutes at a villa rented for him by Oxfam.
The staff had been in Haiti as part of the relief effort following the devastating magnitude 7.0 earthquake that killed more than 200,000 people there in 2010.
The government's review of its relationship with Oxfam comes amid fresh allegations in the paper that the charity failed to alert other aid agencies about the staff members' behaviour.
Mr Van Hauwermeiren went on to work elsewhere in the sector.
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Meanwhile an Oxfam spokeswoman has said the charity would not have provided a positive reference for any of those who were dismissed or resigned.
But she said: "Unfortunately, there is nothing we can do to stop individuals falsifying references, getting others that were dismissed to act as referees and claiming it was a reference from Oxfam, or former or current Oxfam staff that worked with the individual providing a reference in a personal capacity."
In a statement on Friday, the charity said: "The behaviour of some members of Oxfam staff uncovered in Haiti in 2011 was totally unacceptable, contrary to our values and the high standards we expect of our staff.
"Our primary aim was always to root out and take action against those involved and we publicly announced, including to media, both the investigation and the action we took as a result."
The foreign aid debate
By Emma Vardy, BBC political correspondent
Public confidence in the way Britain's foreign aid money is spent has been undermined by a number of scandals.
DfID will now be under pressure to ensure there is zero tolerance of sexual misconduct within agencies that receive government aid funds.
It is unclear to what extent DfID may have been made aware of the Oxfam incident back in 2011.
Similar cases involving UN peacekeeping soldiers were brought to the attention of the then International Development Secretary Andrew Mitchell.
The UK currently spends £13bn on aid each year and there have long been calls from some Conservative MPs for cuts to this budget.
But Theresa May says she is "proud" of the UK's record on foreign aid and remains committed to the UK's requirement to spend 0.7% of the country's gross national income on overseas assistance.
Labour, the Liberal Democrats, SNP, Greens and Plaid Cymru also agree that figure should remain.
'Lack of judgement'
A DfID spokesman said the way "appalling abuse of vulnerable people" had been dealt with raised serious questions for Oxfam.
He said the department acknowledged that hundreds of Oxfam staff had done nothing wrong, "but the handling by the senior team about this investigation and their openness with us and the charity commission showed a lack of judgement".
"We have a zero tolerance policy for the type of activity that took place in this instance, and we expect our partners to as well," the spokesman said.
"We often work with organisations in chaotic and difficult circumstances. If wrongdoing, abuse, fraud, or criminal activity occur we need to know about it immediately, in full."
International Development Secretary Penny Mordaunt had requested a meeting with Oxfam's senior team "at the earliest opportunity", the spokesman said.
Andrew Mitchell, who was international development secretary in 2011, told BBC's Newsnight it was a "shudderingly awful tale" that was "terrible on every single level".
But he said he could not recall being told about the incident.
Dame Barbara Stocking, who was the head of Oxfam in 2011, told the BBC that the charity had a long record of having a very good code of conduct.
When it happened, she said, new whistle-blowing procedures, safeguarding practises and training were put in place.
She said Oxfam often worked in very difficult locations "where the rule of law isn't going on".