Nica Burns said the nature of the event as a “global one-off” open to anyone who wanted to participate on stage or behind the scenes was under threat because of concerns that its growth was out of control and that exploitation of workers is widespread.

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Ms Burns, who has overseen the running of the Edinburgh Comedy Awards since 1984, said it was vital that people were able to have “freedom of choice” of whether to work in venues that did not have “standard working practices”.

The Edinburgh Festival Fringe is the world's biggest arts festival.

She added: “I would question how many complaints there are from staff and how we measure what the people who do those jobs think.”

Ms Burns pointed out there was a long-standing tradition of work at the Fringe providing an initial step on the ladder to a career in the entertainment industry, but insisted it could not be seen as a “normal summer job” because of the size and nature of the festival, which has more than 300 venues.

Speaking at the launch of this year’s awards, which are being sponsored for the first time by comedy TV channel Dave, Ms Burns said: “Everything goes back to the original founding idea that we all love – the spirit of the Fringe.

“It was started by performers and has been constantly reinvented by them. They have been uninvited, unfunded, uncurated and unrestricted by anything except talent, determination and how they fund themselves to participate.

“To me the spirit of the Fringe can be summed up in one word: choice. People come because they choose to and that goes beyond performers to embrace all of those who come to work here to deliver the Fringe and drink it all in.

“For performers it offers incredible opportunities, but for anyone else it is not just a summer job. I know many people whose successful jobs in entertainment who started here, working front of house or on street teams, and really muck in.

“It is a life-changing experience. Should all this opportunity to participate be eroded or taken away through restriction and limitation? It’s a festival. It’s a celebration. It’s insane and marvellous. We all go home to the real work to study or work, for less hours, and better conditions, but not half as much fun.”

A dossier highlighting “terrible” and shameful” working practices at the Fringe was published last week by the Fair Fringe campaign, which was launched two years ago.

It raised fresh concerns about the treatment of volunteers, payment and working hours of staff, age discrimination and the use of over-crowded accommodation.

Ms Burns added: “The Fringe is like no other workplace. There should be a much greater understanding of the need for flexibility.

“The Fringe has always been an artist-led free-for-all. Suddenly an awful lot of people are doing reports into it.

“But it’s very much a world one-off because of the sheer size of it. People come here for three weeks to totally devote themselves to the festival, to work, mix and learn.

“If you’re coming here you’re subscribing to being part of an event and not day-to-day work.”

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