The public service broadcaster engaged in a "serious breach" of broadcasting rules by not revealing that the voice of a film about the Gaza conflict was the son of a Hamas official, according to regulatory body Ofcom.
An inquiry by Ofcom into the programme Gaza: How to Survive a Warzone has found that the documentary was "significantly deceptive".
The BBC's director general had already issued an apology, noting there had been "a major oversight in relation to accuracy".
The authority has ordered the broadcaster to air a prime-time announcement about its decisions.
"Given this constitutes a major infringement of our code, we are instructing the broadcaster to transmit a announcement of our determinations against it on BBC2 at nine o'clock in the evening, with a date to be finalised," the statement read.
'Potential to Undermine Credibility'
The watchdog's statement stated: "Our probe found that the film's omission to reveal that the narrator's parent occupied a position in the Hamas-controlled authority was materially misleading.
"This implied that the viewers did not have critical information which may have been very significant to their evaluation of the presenter and the details he presented.
"Trust is at the heart of the connection between a media organization and its audience, especially for a public service broadcaster such as the British Broadcasting Corporation.
"This oversight had the possibility to damage the significantly high amounts of trust that audiences would have invested in a documentary produced by the BBC about the conflict in Gaza."
The documentary was pulled from iPlayer in the month of February after the narrator's family links came to light, and in July an corporation's own inquiry found it infringed the broadcaster's journalistic standards on truthfulness.
A corporation official stated: "The regulator's decision is in line with the conclusions of the corporation's inquiry, that there was a serious error in the film in relation to the BBC's Editorial Guidelines on truthfulness, which corresponds to clause 2.2 of the authority's broadcasting regulations.
"We issued an apology for this and we agree with Ofcom's decision in its entirety. We will adhere to the sanction as soon as the schedule and wording are determined."
