Amira Malik Miller, a former aid worker, claims she alerted her bosses at the British medical emergency relief charity Merlin after serving with van Hauwermeiren there in 2004.
He added: "I feel great responsibility for the trust that you all - as supporters, shoppers, staff and volunteers - place in Oxfam and I know that these devastating reports will have damaged that trust".
In a tweet, she said: "All I can tell you about this very bad revelation about Oxfam is that I am devastated".
The majority of Oxfam's 230 staff members working in Haiti at the time are not accused of doing anything improper, but a small group of male aid workers living in Delmas, near Port-au-Prince, allegedly turned a rented guesthouse into what a source told the Times the men called "the whorehouse".
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The order also represents a win for immigrant rights organizations and the states involved in the suit. The judge's decision follows a similar ruling by a federal court in San Francisco last month.
Fearing that not every detail of the #Haiti accusations have been "disclosed" by the charity, the #Charity Commission in the United Kingdom has launched an inquiry into the organisation in an attempt to figure out if they covered up previous allegations.
Oxfam has denied accusations of a cover-up, saying it launched an internal investigation the moment it became aware of the allegations.
Why van Hauwermeiren was allowed to continue working with vulnerable people for major worldwide charities has been a subject of questions asked of Oxfam, which faces the loss of funding it receives from the British government.
Speaking to Channel 4 News, she said: "It was a continual fight to try and get more resources".
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Rohit Sharma finally shrugged off his poor run in South Africa with a match-winning century in Port Elizabeth on Tuesday. Last year, Rohit dedicated his third double century to Ritika on the occasion of their second marriage anniversary.
After these revelations, Penny Mordaunt, the Secretary of State for International Development, summoned Oxfam officials to demand all information on this case, threatening to cut the yearly public aid donated to the NGO (€35.7 million in government subsidies in 2017).
Haiti's president Jovenel Moise decried Oxfam's handling of a prostitution scandal in the Caribbean nation, calling the situation a "serious violation of human dignity".
Mordaunt is due to give a speech to representatives from worldwide aid agencies and ministers from over 20 countries at the Agenda 2030 for Children: End Violence Solutions Summit. "And compels us to take action". "The case for the type of work done by Oxfam is too strong to allow it to be undermined by bad behaviour", he said.
Following a report in The Times alleging aid workers within Oxfam paid for sex while on a mission to help those affected by the 2010 quake, people have been forced to think about their donations to the charity.
"Sexual abuse and exploitation is an issue the entire development sector needs to confront", Mordaunt said, calling for a culture that "ensures victims and whistleblowers can come forward without fear".
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