The public service broadcaster was found to have committed a "significant breach" of broadcasting rules by not revealing that the narrator of a programme about Gaza was the son of a Hamas administrator, according to UK media regulator Ofcom.
An inquiry by the broadcasting watchdog into the programme Gaza: How to Survive a Warzone has determined that the documentary was "materially misleading".
The head of the BBC had earlier expressed regret, stating there had been "a significant failing in relation to factual correctness".
The regulator has directed the broadcaster to transmit a peak-time announcement about its conclusions.
"As this represents a major infringement of our regulations, we are directing the broadcaster to broadcast a message of our findings against it on BBC Two at 21:00, with a timing to be finalised," it said.
'Possibility to Erode Trust'
The regulator's report stated: "The inquiry we conducted determined that the film's omission to reveal that the presenter's male guardian occupied a post in the Hamas-run administration was substantially inaccurate.
"Consequently that the audience did not have vital facts which may have been extremely pertinent to their judgment of the voice and the details he presented.
"Confidence is at the heart of the connection between a television network and its viewers, notably for a national broadcasting corporation such as the British Broadcasting Corporation.
"This error had the risk to damage the exceptionally strong amounts of credibility that audiences would have invested in a documentary produced by the BBC about the Israel-Gaza war."
The film was removed from iPlayer in February after the presenter's familial connections came to light, and in July an corporation's own inquiry determined it infringed the organization's content policies on accuracy.
A BBC spokesperson commented: "The authority's determination is in agreement with the conclusions of the corporation's inquiry, that there was a serious error in the programme in relation to the broadcaster's journalistic policies on accuracy, which reflects Rule 2.2 of the authority's broadcasting regulations.
"We expressed regret for this and we comply with the regulator's ruling in full. We will follow the sanction as soon as the timing and wording are determined."
