Former aid worker Andrew MacLeod says people need to go to jail to stop Oxfam-style scandals being repeated in future.
MacLeod also said the issue of sex abuse in the aid sector dates back three decades and has even been covered up by the United Nations.
Oxfam continues to face the fall-out from allegations that it covered up the use of prostitutes by aid workers in Haiti following the country's 2010 earthquake. Although a number of staff were sacked or allowed to resign following an internal inquiry, it is claimed that Oxfam did not properly inform government authorities.
MacLeod, who has previously worked for the UN himself, said it still hasn't been proved that none of the prostitutes was a child, meaning offenders could have broken UK sex tourism laws.
If Oxfam are serious about dealing with this crisis, MacLeod said, the charity should take its dossier to Scotland Yard. He added that trustees are not exempt from scrutiny as they have been repeatedly warned that this was a problem, with former UN chiefs Kofi Annan and Ban Ki-moon among those who have spoken out about it.
Ultimately, Macleod said,"we have to put people in jail".
He added that, during his time at the UN, he saw evidence of an "system-wide institutional cover-up" and anyone who tried to blow the whistle was forced out.
Oxfam admits the behaviour of some staff members was inappropriate, but denies a cover-up. The charity also says it is putting robust new measures in place to prevent such problems in future.