The BBC has been accused of being "frivolous" with licence fee-payers' money after it revealed that more than £10m was spent on flights last year.
More than £3m of the total was spent on business or first class flights, according to figures released to the Liberal Democrats under the Freedom of Information Act.
Lib Dem transport spokesman Norman Baker said that at a time when the BBC should be doing all it could to give good value to fee-payers, the figures were "staggering".
He said: "The BBC's own guidelines say that flying business class should only happen in 'exceptional circumstances'. It is hard to believe that there can be £3m worth of exceptional circumstances in a single year.
"Licence fee-payers have a right to assume their money is not being splashed around frivolously. BBC bosses must make sure that, where possible, their staff use trains rather than planes and that when they must fly, they get the best value for money possible."
In a letter sent to the Lib Dems last year outlining the BBC's expenses policy, a spokesman said that wherever possible, audio and video conference facilities should be used as a preferable alternative to travelling.
If this was not appropriate, BBC travellers should use the lowest cost means of travel and fare. Only in "exceptional circumstances" could upgraded travel be justified.
A BBC spokesman said: "We reject these claims completely. Spend on flights is subject to rigorous scrutiny and has actually fallen significantly in the last year, reflecting our commitment to value for money.
"As an international broadcaster, viewers expect us to report stories and bring them programmes from around the world, which inevitably involves travel.
"It is important to make clear this information includes flights by BBC Worldwide so it is completely misleading to suggest this is all money from the licence fee."

Dods Parliamentary Communications Ltd