BBC services including World Service radio were disrupted on Thursday as journalists held a 12-hour strike over job cuts, their second in as many months.
Members of the National Union of Journalists (NUJ) and the technicians' union Bectu across Britain walked out at midday (1200 GMT), holding placards and badges reading "Fight for the BBC".
The BBC News 24 TV channel and World Service radio switched to pre-recorded programming, interspersed with live news bulletins on the hour, while BBC feeds to US public radio were also disrupted.
Paul Mason, economics correspondent for flagship current affairs TV show Newsnight, tweeted: "Just uploaded my report on the opening of Cyprus banks at 1155 GMT... On strike in 5 minutes."
The BBC, the world's largest public broadcaster, said it was "extremely disappointed" at the walkout, which follows a 24-hour strike in February.
NUJ general secretary Michelle Stanistreet said members wanted to send "a clear message to the BBC that it needs to listen to its staff and address properly the problems created by its ill-conceived and badly implemented cuts programme".
The union claims the British Broadcasting Corporation has lost more than 7,000 jobs since 2004 and it plans to cut a further 2,000 jobs as it slashes its budget by 20 percent.
The budget cuts are being driven by a government-ordered reduction in the revenue the corporation gets from the licence fee, which is paid by everyone in Britain with a television.
Unions want a six-month moratorium on the cost-cutting programme to discuss its impact but the BBC says delays would only create more costs.
The NUJ says the plans are causing "unacceptable workloads and stress" and claims management is using the cuts programme as a means to harass and bully staff.
A BBC spokesman said: "We are extremely disappointed that the unions have gone ahead with the strike and apologise to our audiences for the disruption to services."
He said the corporation agreed that stress and workloads "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," he said.