The BBC committed a "major breach" of broadcasting rules by failing to disclose that the voice of a programme about Gaza was the son of a Hamas official, as ruled by British broadcasting authority Ofcom.
An investigation by Ofcom into the documentary titled Gaza: How to Survive a Warzone has found that the documentary was "materially misleading".
The BBC's director general had previously apologised, saying there had been "a significant failing in relation to truthfulness".
Ofcom has directed the BBC to air a prime-time announcement about its conclusions.
"Since this amounts to a serious breach of our regulations, we are ordering the broadcaster to air a announcement of our determinations against it on the BBC's second channel at nine o'clock in the evening, with a timing to be finalised," the statement read.
'Possibility to Erode Credibility'
The regulator's announcement said: "Our probe determined that the programme's lack of disclosure that the voice's parent occupied a post in the Hamas-controlled government was significantly deceptive.
"This implied that the public did not have critical information which may have been extremely pertinent to their evaluation of the voice and the information he presented.
"Trust is at the center of the connection between a television network and its audience, notably for a public service broadcaster such as the BBC.
"This failing had the potential to undermine the very considerable degrees of trust that audiences would have invested in a documentary produced by the BBC about the conflict in Gaza."
The film was removed from the BBC's streaming service in last February after the narrator's familial connections emerged, and in the month of July an corporation's own inquiry determined it violated the organization's journalistic standards on factual correctness.
A representative for the broadcaster stated: "The regulator's decision is in agreement with the results 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 corresponds to regulation 2.2 of the regulator's media standards.
"We have apologised for this and we accept Ofcom's decision in its entirety. We will follow the directive as soon as the timing and wording are finalised."
