The BBC committed a "major breach" of broadcasting rules by not revealing that the voice of a documentary about the Gaza situation was the offspring of a Hamas official, as ruled by UK media regulator Ofcom.
An probe by Ofcom into Gaza: How to Survive a Warzone has found that the documentary was "materially misleading".
The chief executive of the broadcaster had already issued an apology, noting there had been "a serious error in relation to accuracy".
Ofcom has instructed the corporation to transmit a prime-time announcement about its conclusions.
"Given this constitutes a major infringement of our code, we are directing the corporation to transmit a message of our determinations against it on the BBC's second channel at 9pm, with a schedule to be confirmed," it said.
'Risk to Undermine Trust'
The watchdog's statement said: "Our probe found that the programme's omission to reveal that the voice's male guardian served in a position in the Hamas-run authority was significantly deceptive.
"Consequently that the viewers did not have vital facts which may have been very significant to their assessment of the narrator and the content he presented.
"Trust is at the core of the relationship between a broadcaster and its public, especially for a public service broadcaster such as the British Broadcasting Corporation.
"This error had the potential to erode the significantly high degrees of trust that viewers would have put in a BBC factual programme about the conflict in Gaza."
The programme was withdrawn from the BBC's streaming service in last February after the narrator's personal associations came to light, and in the month of July an broadcaster's internal assessment determined it infringed the corporation's content policies on factual correctness.
A corporation official stated: "The Ofcom ruling is in accordance with the results of the internal assessment, that there was a major oversight in the film in relation to the broadcaster's journalistic policies on accuracy, which reflects regulation 2.2 of Ofcom's Broadcasting Code.
"We expressed regret for this and we comply with the authority's determination in full. We will adhere to the penalty as soon as the timing and language are confirmed."
