The public service broadcaster committed a "major breach" of industry standards by failing to disclose that the narrator of a programme about Gaza was the son of a Hamas administrator, as determined by regulatory body Ofcom.
An inquiry by the media regulator into Gaza: How to Survive a Warzone has concluded that the film was "substantially inaccurate".
The BBC's director general had previously apologised, saying there had been "a significant failing in relation to factual correctness".
The regulator has ordered the broadcaster to broadcast a evening announcement about its decisions.
"Since this amounts to a serious breach of our rules, we are directing the corporation to air a announcement of our conclusions against it on BBC2 at nine o'clock in the evening, with a date to be finalised," the regulator stated.
'Risk to Erode Credibility'
The watchdog's report declared: "The inquiry we conducted determined that the programme's omission to reveal that the narrator's male guardian occupied a position in the Hamas-controlled administration was substantially inaccurate.
"This implied that the audience did not have vital facts which may have been highly relevant to their judgment of the voice and the details he presented.
"Credibility is at the center of the relationship between a media organization and its viewers, particularly for a state-funded media outlet such as the British Broadcasting Corporation.
"This failing had the possibility to damage the exceptionally strong amounts of credibility that viewers would have placed in a factual film from the broadcaster about the Israel-Gaza war."
The documentary was withdrawn from the BBC's streaming service in February after the boy's familial connections emerged, and in July an broadcaster's internal assessment concluded it violated the corporation's journalistic standards on accuracy.
A BBC spokesperson stated: "The authority's determination is in agreement with the conclusions 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 aligns with clause 2.2 of Ofcom's Broadcasting Code.
"We issued an apology for this and we accept the regulator's ruling in its entirety. We will comply with the penalty as soon as the schedule and wording are finalised."
