The BBC engaged in a "significant breach" of media regulations by not revealing that the narrator of a programme about the Gaza situation was the child of a Hamas official, according to British broadcasting authority Ofcom.
An probe by Ofcom into Gaza: How to Survive a Warzone has concluded that the film was "materially misleading".
The BBC's director general had already issued an apology, noting there had been "a significant failing in relation to truthfulness".
Ofcom has directed the BBC to air a peak-time announcement about its conclusions.
"Since this amounts to a serious breach of our regulations, we are directing the broadcaster to broadcast a announcement of our determinations against it on BBC Two at 21:00, with a schedule to be finalised," it said.
'Potential to Damage Trust'
The regulator's announcement declared: "The inquiry we conducted concluded that the film's failure to disclose that the narrator's parent held a role in the Hamas-administered government was substantially inaccurate.
"This implied that the audience did not have essential details which may have been very significant to their evaluation of the narrator and the content he provided.
"Credibility is at the core of the relationship between a media organization and its audience, notably for a state-funded media outlet such as the British Broadcasting Corporation.
"This error had the possibility to undermine the exceptionally strong degrees of confidence that the public would have invested in a documentary produced by the BBC about the conflict in Gaza."
The documentary was removed from the BBC's streaming service in the month of February after the presenter's familial connections were revealed, and in July an broadcaster's internal assessment determined it violated the broadcaster's editorial guidelines on accuracy.
A corporation official stated: "The regulator's decision is in accordance with the conclusions of the corporation's inquiry, that there was a significant failing in the film in relation to the BBC's Editorial Guidelines on factual correctness, which aligns with regulation 2.2 of Ofcom's Broadcasting Code.
"We expressed regret for this and we comply with the authority's determination in complete. We will adhere to the penalty as soon as the schedule and wording are finalised."
