The head of the International Atomic Energy Agency, Mohammed El Baradei, has cancelled two interviews with the BBC in protest at a decision not to broadcast a charity appeal for Gaza.
A spokesperson for Mr El Baradei says he believes the decision violates the rules of basic human decency.
BBC director-general Mark Thompson has said that broadcasting the concert could compromise the BBC's impartiality.
The BBC says it regrets Mr El Baradei's decision.
ITV, Channel 4 and Five broadcast the appeal on Monday. Sky News also chose not to air it, saying it would be "incompatible" with its objective role.