The BBC engaged in a "serious breach" of broadcasting rules by omitting to mention that the narrator of a programme about the Gaza conflict was the son of a Hamas representative, according to UK media regulator Ofcom.
An inquiry by Ofcom into Gaza: How to Survive a Warzone has found that the programme was "materially misleading".
The head of the BBC had already issued an apology, noting there had been "a major oversight in relation to accuracy".
The authority has instructed the broadcaster to transmit a evening announcement about its findings.
"Since this amounts to a significant violation of our code, we are ordering the broadcaster to air a announcement of our determinations against it on BBC2 at nine o'clock in the evening, with a timing to be determined," the regulator stated.
'Risk to Damage Confidence'
The authority's statement stated: "The inquiry we conducted found that the documentary's failure to disclose that the voice's parent served in a role in the Hamas-run administration was materially misleading.
"This implied that the public did not have critical information which may have been very significant to their judgment of the voice and the content he shared.
"Credibility is at the center of the relationship between a television network and its viewers, particularly for a state-funded media outlet such as the British Broadcasting Corporation.
"This failing had the risk to damage the exceptionally strong levels of confidence 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The documentary was withdrawn from the BBC's streaming service in last February after the boy's family links emerged, and in the month of July an broadcaster's internal assessment concluded it infringed the broadcaster's content policies on accuracy.
A representative for the broadcaster stated: "The regulator's decision is in agreement with the findings of Peter Johnston's review, that there was a serious error in the programme in relation to the broadcaster's journalistic policies on factual correctness, which aligns with clause 2.2 of Ofcom's Broadcasting Code.
"We issued an apology for this and we agree with the regulator's ruling in its entirety. We will comply with the directive as soon as the date and language are determined."
