A version of Aida has been performed at Cairo's Pyramids of Giza

Mr Brown stressed the union is seeking only "to give performers a voice".

"We have no problem with Mr Gubbay's contracts or rates of pay," he added.

Up to 40,000 tickets have already been sold for the production of Aida which opens at The Royal Albert Hall later this month, before going on tour across the country.

Much of Mr Gubbay's success is put down to his relatively low ticket prices, in contrast to establishments such as the Royal Opera House.

But the impresario told The Independent he would not stage any more of his "spectaculars" unless Equity caved in on its demands.

'Stir up trouble'

"The whole concept of this sort of opera is now under threat," he said.

"There's a couple of million pounds riding on the Aida. If they stir up trouble like this, I won't put on productions in the future," he told the Independent.

Mr Gubbay recently missed out on the job of executive director at the Royal Opera House. The position went to Tony Hall, former head of news and current affairs at the BBC.