The BBC engaged in a "major breach" of media regulations by failing to disclose that the voice of a programme about Gaza was the offspring of a Hamas administrator, according to regulatory body Ofcom.
An investigation by the media regulator into Gaza: How to Survive a Warzone has determined that the film was "substantially inaccurate".
The BBC's director general had previously apologised, noting there had been "a serious error in relation to truthfulness".
Ofcom has instructed the BBC to air a peak-time statement about its decisions.
"Given this constitutes a significant violation of our code, we are directing the corporation to transmit a announcement of our conclusions against it on BBC Two at nine o'clock in the evening, with a schedule to be finalised," the statement read.
'Possibility to Undermine Credibility'
The watchdog's announcement stated: "The inquiry we conducted determined that the documentary's omission to reveal that the voice's parent served in a position in the Hamas-administered government was significantly deceptive.
"Consequently that the viewers did not have vital facts which may have been very significant to their evaluation of the voice and the information he provided.
"Confidence is at the center of the connection between a television network and its audience, notably for a national broadcasting corporation such as the British Broadcasting Corporation.
"This failing had the possibility to erode the exceptionally strong degrees of confidence that audiences would have placed in a documentary produced by the BBC about the Gaza conflict."
The documentary was pulled from iPlayer in February after the narrator's personal associations were revealed, and in this past July an internal BBC review found it breached the broadcaster's editorial guidelines on factual correctness.
A BBC spokesperson stated: "The regulator's decision is in accordance with the conclusions 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 corresponds to regulation 2.2 of the authority's broadcasting regulations.
"We have apologised for this and we accept the regulator's ruling in complete. We will comply with the directive as soon as the timing and wording are determined."
