Almost 3,000 theatre jobs are at risk under current redundancy plans in the sector, which has been described by BECTU as "cultural vandalism beyond repair".
The entertainment union told The Stage the figure is based on official notifications it has received from employers currently carrying out redundancy consultations with staff.
The affected roles include those in front of house, creative and technical roles and management positions, and the number is expected to continue to rise. The number does not include freelancers, who make up about 70% of the industry.
It comes as theatres across the UK make job cuts in order to navigate the pandemic, with the Royal Exchange in Manchester among the recent organisations to announce redundancies.
BECTU said it had members working in other organisations making job cuts, including Southampton Nuffield Theatres, Theatre Royal Plymouth, the Royal Albert Hall, the Royal Opera House, Lyceum Edinburgh, National Theatre, Nimax Theatres, Cameron Mackintosh and Delfont Mackintosh, Birmingham Hippodrome, Coventry Belgrade, Theatre Royal Newcastle and others.
BECTU head Philippa Childs said: “A perfect storm is taking place across the theatre industry, which is only set to turn into a tsunami as each day passes without government intervention. The clock has been ticking since it was announced that employers will have to contribute to furlough scheme from August.”
“BECTU officials have been working night and day to save these people’s jobs, but the reality is that theatres have no income coming in and no plan for when they can truly start to operate again,” she added.
She described the losses as “cultural vandalism beyond repair”.
“Many theatre industry workers are freelance and have fallen through the gaps of the income support schemes and received no government help. The government has failed these people at every stage of this crisis,” she said, adding that chancellor Rishi Sunak is making a statement July 8 and “so much hangs on whether the government acts to provide a comprehensive rescue and recovery package”.
“That package must include a short-term cash injection to allow theatres to remain open, a specific exemption for theatres to contribute to the furlough scheme and support for freelancers currently excluded from financial support. We also need a long-term plan for how live performances can take place again and the money to allow that to happen,” she added.
Figures from SOLT and UK Theatre estimate theatres employ around 290,000 people.
Theatres first began issuing redundancy notices in May after it was announced employers will need to start contributing to the furlough scheme from August.
The government, including culture secretary Oliver Dowden, is facing increasing pressure to provide a rescue package for the sector, after a roadmap released last week was branded "meaningless" by industry figures.
This week, The Stage launched a campaign calling on the government to take action to address the situation in the sector.