Thousands of BBC staff are to be balloted for strikes in a row over jobs, pay and conditions, raising the threat of disruption to flagship programmes including Strictly Come Dancing.
Technicians, journalists and other employees will vote from November 4 on whether to take industrial action, with union leaders not ruling out targeting coverage of next year's Olympic Games in London.
The BBC unveiled plans earlier this month to axe 2,000 jobs and make changes to terms and conditions to make savings of 20%, worth £670 million a year by 2016/17.
Talks have since been held between the corporation and unions - Bectu, the National Union of Journalists and Unite - on the changes, but no agreement has been reached.
Unions said they had been pressing the BBC without success to lift deadlines for change included in the proposals.
Bectu general secretary Gerry Morrissey said the corporation wanted to introduce different terms and conditions for new staff from next April, adding: "We are not prepared to negotiate with a gun to our head."
The ballot result will be known on November 24, so industrial action could start in early December if there is a yes vote.
Mr Morrissey warned that programmes such as the final stages of Strictly Come Dancing and the BBC's Sports Personality Of The Year could be hit. Union sources said next year's Olympics could be targeted if the dispute is not resolved.
"We want a proper structure for dealing with job losses," said the Bectu leader, who described the BBC's Delivering Quality First Programme as "Destroying Quality First".
A BBC spokesman said: "We are fully committed to a constructive dialogue with the unions about flexibility allowances and our pay and grading structure. However we are at the earliest stage of talking these proposals through with our staff and have not even begun formal consultation with the trade unions."