Sexual abuse of vulnerable women and girls by international aid workers is “endemic” and has been happening for years, with perpetrators easily moving around the sector undetected, according to a UK government report published Tuesday.

The report by the House of Commons International Development Committee comes after historical allegations of harassment and sexual misconduct by employees of several top NGOs, including Oxfam and Save the Children, surfaced earlier this year. Those allegations prompted the Committee to launch an inquiry into abuse in the aid sector in February.

Tuesday’s report found sexual abuse and exploitation to be “endemic across the international aid sector” and targeted at both locals and staff members. Abuses ranged from unwanted sexual comments to rape.

“The power imbalance is predominantly, although not exclusively, men abusing women and girls,” said the report, which warned that the cases that had come to light were likely just the “tip of the iceberg

A cause of “deep concern and alarm” was the ease with which individuals known to be predatory or potentially dangerous were able to move undetected from one aid organization to another, the report added.

The committee criticized aid groups for failing to tackle the problem despite being aware of reports of abuse for years. Chair of the committee, MP Stephen Twigg, said that the report set out “the collective failure over period of at least 16 years by the aid sector to address sexual exploitation and abuse.”

He said that in effect, organizations had often put “their reputation ahead of women, children and other victims of sexual exploitation and abuse.”