The British broadcaster engaged in a "significant breach" of media regulations by not revealing that the narrator of a documentary about the Gaza conflict was the offspring of a Hamas administrator, according to British broadcasting authority Ofcom.
An probe by the broadcasting watchdog into Gaza: How to Survive a Warzone has determined that the documentary was "substantially inaccurate".
The chief executive of the broadcaster had earlier expressed regret, saying there had been "a serious error in relation to accuracy".
Ofcom has instructed the broadcaster to transmit a peak-time declaration about its findings.
"Since this amounts to a significant violation of our code, we are directing the corporation to broadcast a message of our findings against it on BBC2 at 21:00, with a date to be finalised," the regulator stated.
The regulator's statement said: "Our probe found that the film's failure to disclose that the presenter's father held a position in the Hamas-controlled government 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.
"Trust is at the core of the bond between a media organization and its audience, notably for a national broadcasting corporation such as the public broadcaster.
"This error had the possibility to damage the exceptionally strong levels of confidence that viewers would have put in a BBC factual programme about the conflict in Gaza."
The documentary was removed from iPlayer in the month of February after the presenter's personal associations emerged, and in July an internal BBC review found it breached the corporation's editorial guidelines on accuracy.
A representative for the broadcaster said: "The Ofcom ruling is in accordance with the findings 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 Rule 2.2 of Ofcom's Broadcasting Code.
"We issued an apology for this and we comply with the regulator's ruling in full. We will adhere to the sanction as soon as the date and wording are confirmed."
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