BBC radio and TV programmes are being disrupted because of a strike by journalists and technical staff in a row over jobs, workload and claims of bullying, with threats of further stoppages to come.
Members of the National Union of Journalists (NUJ) and the technicians' union Bectu walked out of offices and studios across the UK at noon on Thursday and will follow the action with a work to rule.
The strike will last until midnight and has led to the cancellation of BBC2's Newsnight, Radio 4's PM and World Tonight, with pre-recorded interviews being used on the news channel as well as other changes.
Unions mounted picket lines outside BBC centres, including New Broadcasting House in central London, where strikers held up banners and wore badges which read Fight For The BBC.
The unions were protesting against the so-called Delivering Quality First (DQF) programme which will lead to 2,000 job losses. The BBC apologised for disruption caused by the strike but said it could not agree to union calls for compulsory job losses to be postponed.
Michelle Stanistreet, general secretary of the NUJ, who joined strikers in London, said workers are sending a clear message to the BBC that it needs to address problems created by the "ill-conceived and badly-implemented" cuts.
She said: "It is disappointing that once again the BBC has decided not to properly engage, refusing our call for a moratorium to give space for meaningful discussions on the worrying impact of the cuts. The DQF plans remain on the table, regardless of the consequence for workload and stress levels.
"We know that the cuts are already having an impact on the quality of work. We know that it is leading to unacceptable workloads and stress. We know that management is using DQF as a means to harass and bully staff - making worse an already entrenched problem of bullying that has been largely ignored by those in positions of power."
A BBC spokesman said: "We have had constructive meetings with the unions in recent weeks and whilst we're unable to postpone planned compulsory redundancies for six months as they requested, we do agree that stress and workload are areas of real concern.
"If workloads are going up because of the pressures of working in a 24/7 digital media environment and implementing savings, it's in everyone's interest to understand the issues and work with individuals, their managers and the unions to address it."