The public service broadcaster committed a "major breach" of media regulations by failing to disclose that the presenter of a programme about the Gaza situation was the offspring of a Hamas official, as ruled by UK media regulator Ofcom.
An probe by Ofcom into the programme Gaza: How to Survive a Warzone has determined that the documentary was "significantly deceptive".
The chief executive of the broadcaster had already issued an apology, noting there had been "a serious error in relation to accuracy".
The authority has directed the BBC to air a peak-time declaration about its findings.
"Given this constitutes a major infringement of our regulations, we are instructing the broadcaster to transmit a announcement of our findings against it on BBC Two at nine o'clock in the evening, with a schedule to be determined," it said.
'Potential to Erode Credibility'
The authority's announcement stated: "Our probe determined that the film's omission to reveal that the narrator's male guardian occupied a role in the Hamas-controlled administration was substantially inaccurate.
"This implied that the public did not have critical information which may have been extremely pertinent to their evaluation of the voice and the information he provided.
"Trust is at the center of the connection between a media organization and its public, especially for a national broadcasting corporation such as the public broadcaster.
"This oversight had the risk to damage the very considerable levels of credibility that audiences would have invested in a documentary produced by the BBC about the Israel-Gaza war."
The documentary was withdrawn from the BBC's streaming service in the month of February after the narrator's family links emerged, and in July an corporation's own inquiry determined it violated the broadcaster's content policies on factual correctness.
A representative for the broadcaster stated: "The regulator's decision is in accordance with the results of Peter Johnston's review, that there was a major oversight in the programme in relation to the broadcaster's journalistic policies on accuracy, which reflects clause 2.2 of the authority's broadcasting regulations.
"We expressed regret for this and we comply with the authority's determination in complete. We will adhere to the sanction as soon as the timing and language are determined."
