Thousands of BBC workers are to stage two 48-hour strikes in a row over pensions which threatens the corporation's coverage of the Conservative Party conference and the Government's comprehensive spending review.
Journalists, technicians and other broadcast staff will walk out on October 5 and 6, when the Conservative conference will be held, and again on October 19 and 20, the date of the spending review.
The action was announced by Bectu, the National Union of Journalists and Unite even though the BBC offered a new concession in an attempt to avert strikes.
Unions will consult with their members over the next few weeks before meeting on October 1 to decide whether to press ahead with the strikes.
Gerry Morrissey, Bectu's general secretary, said: "Whilst the BBC has heard and responded to some of our concerns, we are disappointed that the BBC's response fails to take account of the long-term implications of the worsening of pension terms for staff and their families.
"We believe that the BBC should be prepared to justify its position fully by agreeing to revisit pension benefits in April 2011, should official figures confirm that the total scheme deficit is less than £1.5 billion. That said, the latest proposals from the BBC warrant further detailed examination with members."
Jeremy Dear, NUJ general secretary said: "The BBC's continued insistence that staff pay much more for significantly worse benefits is unacceptable. We will be taking the union's case for fair pensions to a series of members' meetings across the UK.
"If the BBC fails to listen to the continued anger of staff at these unacceptable pensions changes, we will be left with no choice but to strike to stop the pensions robbery.
"Our strong and determined stand against the BBC's pensions robbery has resulted in today's proposals. We continue to believe they are unacceptable and unfair.
"We will consult with members, give the BBC the chance to address our ongoing concerns. If they fail to do so, they will face strike action."