The BBC World Service is to close five of its language services with hundreds of job losses expected.
It is thought about 650 jobs will be cut from a workforce of some 2,400 in a bid to save £46 million a year.
Union leaders said the "ferocious cuts" were a "direct result of the Government slashing funding to an internationally respected and successful broadcaster".
The corporation said in a statement: "BBC World Service has announced that it will be closing five language services - Albanian, Macedonian, Portuguese for Africa and Serbian; as well as the English for the Caribbean regional service.
"This is part of its response to a cut to its Grant-in-Aid funding from the UK's Foreign and Commonwealth Office.
"The cut is part of a BBC World Service restructure in order to meet a 16% savings target announced in the Government's spending review of October 20th last year."
BBC Global News Director Peter Horrocks said: "These closures are not a reflection on the performance of individual services or programmes. They are all extremely important to their audiences and to the BBC.