One of Britain’s largest charities is under fire following an investigation into claims of sexual exploitation of underage girls by senior aid workers in Haiti.

An investigation by The Times UK revealed that Oxfam, which receives £300 million ($414 million U.S. dollars) in British government funds and charitable donations, let three staffers resign and fired four others for gross misconduct after an inquiry into the damning claims.

A confidential report by the charity said there’d been a “culture of impunity” among some of the workers in Haiti, who were there as part of international relief efforts to help those impacted by the devastating earthquake of 2010. One of the staffers permitted to resign without consequence was Oxfam country director Roland van Hauwermeiren, 68, who the report said admitted to keeping prostitutes at the villa rented for him using donated funds.

“It cannot be ruled out that any of the prostitutes were under-aged,” the 2011 report read.

Even after Hauwermeiren’s admission, then-chief executive Dame Barbara Stocking offered the disgraced aid worker a “phased and dignified exit,” for fear that terminating him would have potentially serious implications” for the charity’s global reputation.

Sources familiar with the case said they were worried some of the prostitutes were underage. One reported that the men would invite young girls to their guest house to have sex “parties.” There is also reportedly footage from a night one of the sources described as a “full-on Caligula orgy” with girls dressed in nothing but Oxfam t-shirts.

“In case you were wondering, teenage girls, in one of the poorest countries in the world, immediately following an earthquake don’t by any measure ‘choose’ prostitution,” Gavin Shuker, Labour MP for Luton South, said of the revelation.

Oxfam officials said they never reported the sexual misconduct to Haitian police because it was “extremely unlikely that any action would be taken.” There are also conflicting reports over whether Oxfam ever reported the incidents to the Charity Commission as it claimed to have done. Still, none of the accused staffers have been arrested or faced criminal charges.

What’s worse, the charity acknowledged that the staff in Haiti felt intimidated and unable to blow the whistle on the abuse, according to The Times. An unidentified source familiar with the investigation alleged that Oxfam bosses thought it “unnecessary to pursue some of the allegations if we could get enough to simply dismiss the individuals.”

The charity issued the following statement in response to the allegations:

“Oxfam treats any allegation of misconduct extremely seriously. As soon as we became aware of a range of allegations — including of sexual misconduct — in Haiti in 2011 we launched an internal investigation. The investigation was announced publicly and staff members were suspended pending the outcome.”