The issue came to light in a bitter exchange on Facebook that was later deleted.

In one of the comments seen by the Telegraph, a male volunteer from Exeter wrote: “I know of at least one volunteer ... that has exploited women by offering them food and shelter in return for sex. I’m sure this is not a unique incident.”

Another female volunteer said she had heard reports of trading “sex for aid” and added: “There are also lots of women (mainly French) who are using men for sex and a florid prostitution business around men who live in the jungle, paid five or seven euros.”

She said the “shameful behaviour” of these female volunteers “is causing a lot of resentment, and all women are [tarred] with the same brush”.