Half of the directors working in British theatre, some on the country’s most prestigious stages, are earning less than £5,000 a year, according to research. The news coincides with warnings that “brilliant minds” are being forced out of theatre, unable to make a decent living.

A survey by the industry group Stage Directors UK found the average salary for directors in subsidised theatres was £10,759, far below the average national wage of £26,500. Some were being paid the equivalent of less than £1 an hour.

The figures have highlighted concerns that theatre is becoming the preserve of the wealthy and privileged, with low wages making it unaffordable for those without other income or financial support.

The report says that “at entry level and on the fringe, matters are even worse”. “£1,500 is common [for several months’ work], £200 is not unheard of, and many productions pay nothing at all, or sacrifice the director’s fee the moment funding runs short. It is not surprising, then, that some talented people without alternative sources of income are forced to leave the profession at all stages.”

Matthew Xia, associate artistic director of the Manchester Royal Exchange, who comes from a low-income, single parent, east London background, said he had been consistently forced to subsidise his income by working as a DJ, besides relying on his higher-earning partner. “I think, if you look at the sector and the people who are holding the top positions, running the major theatre organisations, you will find so few of them from a working-class background, and I think that’s one of the biggest hindrances.

“It’s also the same with the number of women who are running organisations, because so often when they have children they are taken out of the workplace and then find it hard to re-enter on a salary that doesn’t allow them to pay for the child care. Without a support network and some kind of financial background, it can be impossible.”

The survey of 346 directors showed the majority in London earned between £2,000 and £3,000 for each production, usually amounting to about two or three months’ work, with more than a fifth earning under £1,000.

In regional theatres almost half the directors earned less than £2,500 for each job. Nationwide, the report showed that directors were unpaid for half the time they worked on a production.

In London, the highest paying subsidised theatre, excluding the National Theatre, was the Almeida, which was paying fees of £6,750 for a production, while outside the capital the highest paying theatre was Chichester, paying £6,993.

The lowest paying London theatre was Soho, paying £670, and, regionally, Sherman Cymru, offering fees of £2,183. Only 5% of directors were found to earn above £7,000 for a directing job at a subsidised London theatre.

Xia said that while theatres were under increasing pressure to diversify their audiences, the lack of those from varied social backgrounds directing in the theatre industry, often because of the low wages, made that a difficult challenge.

Xia said: “The single most direct way you can diversify your audience is to change the content of your production on your stage. That content needs to be generated by someone, and if that person can’t afford to generate that content, then it will never happen.

“If I go back to freelance directing I would only be earning about £9,000 a year, and that’s me fitting in as many shows as is humanly possible, normally about three or four.

“What is increasingly apparent for me is that we are all being asked to diversify across the board organisationally – but how can we do that if the people from low income backgrounds, which often includes people from a diverse range of ethnic backgrounds as well, just can’t sustain themselves working in the industry without financial support?

“I’ve seen so many talented people forced to drop off directing, or step away from the creative side of theatre, because it became unaffordable, which is a shame because we are losing some brilliant minds and really interesting ways of thinking. It will be just [as] Peter Bazalgette said, ‘We will end up with work that is male, pale and stale.’”

The report found that even directors considered successful and established – say, directing four productions a year in prestigious theatres such as the Royal Court, Donmar, Young Vic, or Hampstead Theatre – were earning top salaries of only about £22,000. This pay was found to be considerably lower than that paid to directors working at a similar level abroad; in Germany they earned about £32,600, in Amsterdam £29,900 and in Warsaw £37,260.

Jemma Gross, artistic director of the theatre company Epsilon Productions and a board member of Stage Directors UK, said the figures were depressing. She said she had subsidised her director’s income with office work, drama teaching and time as a children’s entertainer; even then she had required family assistance.

“I’m still struggling up that directing ladder and there is this assumption that when you get to a certain level you will be able to live off what you do. So the shocking realisation that you can’t – that’s been a major revelation to me.

“On a diversity level, it is absolutely a major problem. If I didn’t have the help of my family I just wouldn’t be able to contemplate directing. My biggest concern is that I meet lots of young students and passionate actors who later in life want to bring their wealth of knowledge and experience to directing but have no feasible way of sustaining themselves directing.”

Gross said last week she had seen an advert for an assistant directing job at an off-West End theatre offering only £50 for a month’s work.

“That’s just laughable,” she said. “And I believe it’s already had a negative effect on diversity in terms of the plays on stage … it will continue to have a negative effect because if the only voices really pushing through to mid-range level or higher in theatre are all from a wealthy, privileged background, it means our theatres become homogenous and [do not represent] all voices across society… It means a lot of wonderful potential voices are never going to get heard.”

In fringe theatre, where most directors begin their career and establish their names, 42% were found to be earning under £100.

Robyn Winfield-Smith, assistant director of the arts centre Omnibus in Clapham, London, said she saved for four years before she could afford to pursue directing full time. She echoed concerns about the impact low pay had on diversity in the theatre.

“These figures do substantiate the feeling … that there is a level of underpayment going on, in terms of not valuing amount of time spent. But to see the facts in black and white is shocking,” she said.

“If we continue the way we are, we are not only going to deter people who don’t have the contacts or assets to get into the industry, but make it completely impossible for them to work. I think the pool of directors in this country will stagnate unless we can provide ways in for those at the bottom and give them a sustainable salary.”

David Lan, artistic director of the Young Vic, said: “Of course it impacts on diversity. Even when we can’t pay these directors properly many of those people will nonetheless be driven to make their work, and I respect that … on the other hand if you aren’t paying people properly that is a real problem. We are trying to do a complicated thing on very limited resources.”

• This article was amended on 8 January 2015. It originally referred to a negative “affect” on diversity where “effect” was meant. This has now been corrected.