One of the Oxfam workers sacked over sexual misconduct allegations in earthquake-shattered Haiti was later re-hired by the charity in Ethiopia.
The decision to employ the man as a consultant in the African nation was described by the charity as a “serious error”.
Several staff were sacked or resigned in 2011 over a string of lurid claims, including that they had used prostitutes while delivering aid to Haiti.
Oxfam said in a statement it had identified that “one of those dismissed by Oxfam as a result of the sexual misconduct case in Haiti” was “subsequently hired by Oxfam as a consultant In Ethiopia”.
Hiring the man “even in an emergency as a short-term consultant” was a “serious error and should never have happened”, it continued.
“We are still checking how this occurred but it further highlights that we need an organisation and sector-wide approach to the vetting and recruitment of both staff and consultants, especially in emergencies where there is pressure to fill posts quickly in order to help save lives. ”
The charity is now checking whether there were “any issues” while the man was posted in Ethiopia.
It is the latest revelation in a scandal which has seen the renowned aid charity rocked by a crisis of credibilty.
The Times newspaper first published details of Oxfam’s 2011 inquiry into the allegations, which were never fully disclosed to the public and have now fuelled suspicion of a cover-up.
The former Oxfam chief at the heart of the story broke his silence to dismiss as “lies and exaggerations” allegations that he threw parties with prostitutes.
Roland van Hauwermeiren resigned as Oxfam’s Haiti director when the explosive claims came to light in 2011, moving to another charity in Bangladesh which claimed not to have been warned about the nature of his departure.
Mr van Hauwermeiren admitted certain details that had come to light were accurate.
He told Belgian newspaper De Standaard: “A lot of people, including in the international media, will be blushing with shame when they hear my version of the facts.
“It is not that I deny everything. There are things that are described correctly. But there are many lies and exaggerations.
“Parties every week? Fancy villas? Women paid with money from the organisation?”
He indicated the revelations had taken a personal toll, telling the paper: “It is especially bad that my family no longer want to see me.”
It comes as International Development Secretary Penny Mordaunt was due to meet director-general of the National Crime Agency (NCA) Lynne Owens to discuss how they could jointly tackle sexual exploitation and abuse.
The NCA has been “closely monitoring” allegations of overseas abuse and has said it has a range of powers to investigate certain sexual offences committed outside the UK.
Meanwhile, Oxfam said that it was “too early to tell the impact of the crisis” on donations, but revealed 1,270 people cancelled their direct debits between Saturday and Monday – almost double the average of 600 cancellations per month.
A spokeswoman added: “We are extremely grateful to all those who continue to support us, those who have made additional gifts, and those who have sent messages of support.
“They are determined that the millions of people that Oxfam helps worldwide every year don’t suffer as a result of the actions of a few.”
In further developments, the charity said it also sacked its Haiti country director last year following allegations of “mismanagement” and “inappropriate behaviour”.
But it stressed the dismissal of Damien Berrendorf, who served as the Oxfam’s country director in Haiti from 2012 to 2017, was “not related to sexual misconduct” and was “not connected to the case in 2011”.
The Charity Commission is expected to set out the terms of its statutory inquiry into Oxfam on Thursday, following an all-day meeting with the charity at its offices in Oxford on Wednesday.
Ms Mordaunt has accused the charity of failing to show moral leadership by not properly informing donors about the actions of its workers and has made clear its public funding could be at risk.
Oxfam received £31.7 million from the UK Government in 2016/17.