'We acknowledge that hundreds of Oxfam staff have done no wrong and work tirelessly for the people they serve, but the handling by the senior team about this investigation and their openness with us and the charity commission showed a lack of judgement.
Oxfam's chief executive Mark Goldring insisted there was no cover-up, telling the BBC: "We were very open with the public that we were ashamed of the behaviour of our staff. I do not wish to hide behind the fact that these persons did not belong to the Belgian branch of the NGO", Declercq said, adding that no employee of Oxfam Belgium was in Haiti in 2010.
The French charity made pre-employment checks but said that Oxfam "did not share with us any warning regarding [his] unethical conduct, the reasons of his resignation or the results of internal inquiry".
"We will expect the charity to provide us with assurance that it has learnt lessons from past incidents and is taking all necessary steps to safeguard all who come into contact with it", the Charity Commission spokeswoman said.
The government's International Development Secretary Penny Mordaunt has also requested a meeting with Oxfam's senior team at the earliest opportunity to discuss the allegations.
Oxfam said it has now set up a whistleblowing hotline as a result of its 2011 investigation.
Oxfam has denied it organised a cover-up after it emerged senior aid workers in Haiti used prostitutes following the devastating 2010 quake.
The government comes amid fresh allegations in The Times that the charity failed to alert other aid agencies about the staff members' behaviour.
"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 said.
This is the case, according to the Times, of Roland Van Hauwermeiren, 68, forced to resign, as confirmed by Oxfam, from his post as Haiti director of the organization after admitting to having hired prostitutes, and could then become Chef de Mission for Action against Hunger in Bangladesh in 2014. The charity is under growing pressure after an investigation by The Times found young sex workers were hired by senior staff in Haiti after the 2010 natural disaster which devastated the island and left up to 300,000 people dead.
Mercy Corps - which handed a job to one of the culprits - said it had received a positive reference from Oxfam in 2015.
"We often work with organisations in chaotic and hard circumstances", a DfID spokesman said.
"A number of staff were dismissed as a result of the investigation and others left the organization before it was completed".
"This behaviour was totally unacceptable, contrary to our values and the high standards we expect of our staff".
And there was also nothing to stop them from getting former or current staff to provide a reference "in a personal capacity", she said.
Allegations that underage girls may have been involved were not proven.
Haiti, reeling after the January 2010 quake which killed an estimated 200,000 people, was already the victim of another aid worker-created disaster: United Nations relief workers from Nepal reportedly sparked a cholera outbreak on the island which killed thousands.
This is published unedited from the PTI feed.