The BBC was found to have 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 determined by regulatory body Ofcom.
An inquiry by the media regulator into Gaza: How to Survive a Warzone has determined that the film was "materially misleading".
The BBC's director general had previously apologised, saying there had been "a major oversight in relation to accuracy".
The regulator has directed the BBC to transmit a prime-time announcement about its findings.
"Given this constitutes a major infringement of our regulations, we are instructing the BBC to air a statement of our findings against it on BBC2 at 21:00, with a schedule to be finalised," the regulator stated.
'Possibility to Erode Confidence'
The watchdog's report declared: "Our investigation determined that the documentary's failure to disclose that the narrator's male guardian occupied a position in the Hamas-controlled administration was significantly deceptive.
"It meant that the viewers did not have critical information which may have been highly relevant to their assessment of the presenter and the details he presented.
"Confidence is at the center of the connection between a broadcaster and its audience, notably for a public service broadcaster such as the BBC.
"This failing had the possibility to erode the very considerable degrees of confidence that audiences would have put in a BBC factual programme about the Gaza conflict."
The documentary was withdrawn from the online platform in February after the narrator's personal associations emerged, and in the month of July an corporation's own inquiry determined it violated the corporation's journalistic standards on truthfulness.
A representative for the broadcaster commented: "The Ofcom ruling is in agreement with the findings of the internal assessment, that there was a serious error in the documentary in relation to the BBC's Editorial Guidelines on truthfulness, which aligns with Rule 2.2 of Ofcom's Broadcasting Code.
"We expressed regret for this and we agree with Ofcom's decision in full. We will follow the penalty as soon as the timing and wording are finalised."
