The first Oxfam celebrity ambassador has resigned from her role in protest at the sex scandal engulfing the charity.

Minnie Driver, a British actress, stood down after 20 years’ support for the charity claiming she was “horrified” by allegations that some staff were having sex with prostitutes in crisis hit countries.

The resignation comes as it emerges that more than 1,270 people cancelled their monthly donations to the charity in just three days. Those cancellations represent a possible loss of £12,039 a month or £144,468 a year, based on the average monthly donation of £9.48.

Charity bosses fear privately that more celebrities and even corporate sponsors could withdraw their support as the backlash about staff having sex with prostitutes and abuse in charity shops deepens.

In a statement, Ms Driver, 48, said: “I am nothing short of horrified by the allegations against Oxfam International.

“In no uncertain terms do I plan to continue my support of this organization or its leaders. And though it is unfortunate that after 20 years I am no longer able to advocate and defend through this specific framework, social and economic injustice is more globally prevalent than ever. I certainly will not let the abhorrent mistakes of a troubling organization stop me or anyone else from working with good people in this space to support a population of human beings around the world that needs our help.”