“We have had an internal ballot and members have voted by over 90 per cent to proceed to an industrial action ballot. We are proceeding to deal with the legalities and the ballot will be held some time over the next few weeks.

“The last time there was any industrial action at the firm was in 1975 – you are talking 37 years ago. In short, people have said ‘enough is enough.

“Our members have already taken a pay freeze three years ago and they see this as a bridge too far.

“This would be another pay cut because inflation has reached four per cent, and in fact is a higher figure, in terms of increased utility bills, heating, food etc.

“The firm has other orders, but their biggest order at the moment is for the Olympics. It is a highly successful company, considering its size – our members have had a hard time and have weathered the storm.

“Whilst we are pursuing a ballot for industrial action, I am asking the company to return to the negotiating table with an improved offer.”

Dave Allen, Eley’s human resources manager, said: “We are not prepared to comment on the pay issue.”

He confirmed the firm had won Olympic Games orders for the London Games.

Meanwhile, a call has come from general secretary Len McCluskey for the public to engage in “civil disobedience” to defend public services during the fortnight of sport, which kicks off on July 27.

In an interview, Mr McCluskey was asked whether his union had discussed the possibility of strikes during the Olympics.

He replied: “Absolutely, yes. “The attacks that are being launched on public sector workers at the moment are so deep and ideological that the idea the world should arrive in London and have these wonderful Olympic Games as though everything is nice and rosy in the garden is unthinkable. Our very way of life is being attacked.”

Conservative co-chairman Baroness Warsi said: “I am shocked that Unite would sink so low as to spoil this great national event for everyone else. Ed Miliband must urgently order his union cronies to rule out disrupting the Olympics.”

Labour’s Olympics spokeswoman Tessa Jowell said: “If this is a negotiation it should take place in private. Unions and employers should get together and sort it out without threats or disruption to Britain’s Olympics.”