The BBC engaged in a "significant breach" of industry standards by not revealing that the presenter of a programme about the Gaza situation was the offspring of a Hamas administrator, according to UK media regulator Ofcom.
An investigation by the media regulator into the documentary titled Gaza: How to Survive a Warzone has found that the film was "materially misleading".
The BBC's director general had previously apologised, noting there had been "a significant failing in relation to factual correctness".
The authority has instructed the BBC to broadcast a prime-time declaration about its findings.
"As this represents a serious breach of our code, we are ordering the corporation to air a announcement of our findings against it on BBC2 at 9pm, with a schedule to be finalised," it said.
The authority's announcement stated: "Our probe concluded that the documentary's failure to disclose that the presenter's parent occupied a position in the Hamas-run government was significantly deceptive.
"Consequently that the public did not have vital facts which may have been highly relevant to their assessment of the voice and the information he presented.
"Credibility is at the center of the connection between a broadcaster and its public, particularly for a national broadcasting corporation such as the BBC.
"This failing had the possibility to undermine the significantly high degrees of credibility that audiences would have put in a BBC factual programme about the Gaza conflict."
The documentary was removed from the BBC's streaming service in February after the boy's familial connections were revealed, and in July an corporation's own inquiry determined it violated the broadcaster's editorial guidelines on truthfulness.
A BBC spokesperson commented: "The regulator's decision is in accordance with the results of the internal assessment, that there was a serious error in the programme in relation to the BBC's Editorial Guidelines on accuracy, which corresponds to clause 2.2 of Ofcom's Broadcasting Code.
"We have apologised for this and we agree with the authority's determination in its entirety. We will adhere to the sanction as soon as the date and wording are confirmed."
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