Choristers at the crisis-hit English National Opera are to stage a series of strikes against proposed job cuts.
The English National Opera was given a £4.2m grant to survive
The 60 singers will walk out on 25 February when they are due to perform The Trojans - The Capture of Troy at London's Coliseum.
Instead they will hold a free concert in nearby St Paul's Church in Convent Garden for invited guests and supporters.
The choir voted unanimously in favour of taking industrial action after bosses at the ENO threatened to make a third of them redundant as part of a radical cost-cutting scheme.
The ENO was bailed out of its financial difficulties with a £4.1m grant from the Arts Council of England to prevent it going into receivership.
They believe that the financial challenges facing the ENO can be addressed without critically damaging the company's artistic integrity
But ENO chairman Martin Smith said redundancies were still expected if the company was to survive, angering its members.
A spokesman for the performers' union Equity said: "The chorus regrets being forced into taking industrial action.
"They believe that the financial challenges facing the ENO can be addressed without critically damaging the company's artistic integrity.
"But as the ENO has refused to lift the threat of redundancy, or to talk to them about their ideas for alternative methods for achieving savings, they feel they have no choice but to strike."
He added: "ENO's loyal audience will be the losers if cuts at the ENO rip out its artistic heart."
The union says more performances will be hit by strike action if the threat of redundancy is not lifted or talks are not entered into with Equity.
The ENO has several times been plunged into financial crisis, with grants helping to keep it afloat.
In 1997 the Arts Council gave the ENO a £9.2m grant but trading conditions continued to worsen.
The recent crisis was blamed on too high expectations of box office receipts and the effects of 11 September on tourism.