The public service broadcaster committed a "serious breach" of broadcasting rules by omitting to mention that the narrator of a programme about the Gaza situation was the child of a Hamas representative, as determined by UK media regulator Ofcom.
An investigation by Ofcom into Gaza: How to Survive a Warzone has determined that the documentary was "substantially inaccurate".
The chief executive of the broadcaster had already issued an apology, saying there had been "a significant failing in relation to accuracy".
Ofcom has directed the BBC to transmit a peak-time declaration about its conclusions.
"Since this amounts to a major infringement of our code, we are ordering the broadcaster to broadcast a message of our findings against it on BBC Two at 21:00, with a timing to be determined," it said.
'Possibility to Damage Credibility'
The regulator's announcement declared: "The inquiry we conducted concluded that the programme's omission to reveal that the narrator's male guardian occupied a position in the Hamas-controlled government was significantly deceptive.
"Consequently that the viewers did not have vital facts which may have been extremely pertinent to their evaluation of the voice and the content he presented.
"Confidence is at the core of the bond between a broadcaster and its public, particularly for a state-funded media outlet such as the public broadcaster.
"This error had the potential to undermine the exceptionally strong amounts of credibility that viewers would have invested in a documentary produced by the BBC about the conflict in Gaza."
The documentary was pulled from iPlayer in last February after the narrator's family links came to light, and in this past July an corporation's own inquiry concluded it violated the organization's journalistic standards on accuracy.
A BBC spokesperson said: "The authority's determination is in agreement with the findings of the internal assessment, that there was a serious error in the documentary in relation to the broadcaster's journalistic policies on factual correctness, which aligns with regulation 2.2 of the regulator's media standards.
"We expressed regret for this and we comply with the regulator's ruling in full. We will comply with the penalty as soon as the timing and wording are determined."
