The public service broadcaster committed a "serious breach" of industry standards by omitting to mention that the voice of a film about the Gaza conflict was the son of a Hamas official, as ruled by British broadcasting authority Ofcom.
An investigation by the media regulator into the programme Gaza: How to Survive a Warzone has determined that the documentary was "significantly deceptive".
The head of the BBC had earlier expressed regret, noting there had been "a significant failing in relation to factual correctness".
Ofcom has ordered the corporation to broadcast a peak-time announcement about its findings.
"Given this constitutes a significant violation of our code, we are directing the BBC to air a announcement of our determinations against it on the BBC's second channel at 21:00, with a schedule to be determined," it said.
'Possibility to Damage Confidence'
The regulator's announcement said: "The inquiry we conducted found that the documentary's failure to disclose that the narrator's male guardian served in a post in the Hamas-run administration was significantly deceptive.
"Consequently that the viewers did not have essential details which may have been very significant to their evaluation of the voice and the details he shared.
"Credibility is at the heart of the connection between a broadcaster and its viewers, particularly for a state-funded media outlet such as the public broadcaster.
"This error had the risk to erode the significantly high degrees of trust that the public would have placed in a documentary produced by the BBC about the Gaza conflict."
The documentary was withdrawn from the online platform in last February after the boy's family links were revealed, and in July an internal BBC review determined it violated the broadcaster's journalistic standards on accuracy.
A representative for the broadcaster stated: "The authority's determination is in agreement with the conclusions of the internal assessment, that there was a serious error in the documentary in relation to the broadcaster's journalistic policies on accuracy, which corresponds to clause 2.2 of Ofcom's Broadcasting Code.
"We have apologised for this and we accept the authority's determination in full. We will comply with the sanction as soon as the schedule and wording are finalised."
