The British broadcaster committed a "major breach" of industry standards by not revealing that the voice of a programme about Gaza was the offspring of a Hamas representative, according to regulatory body Ofcom.
An inquiry by Ofcom into Gaza: How to Survive a Warzone has concluded that the film was "significantly deceptive".
The head of the BBC had already issued an apology, saying there had been "a serious error in relation to factual correctness".
Ofcom has directed the broadcaster to transmit a peak-time declaration about its findings.
"Given this constitutes a significant violation of our code, we are instructing the broadcaster to transmit a message of our findings against it on BBC Two at 9pm, with a schedule to be finalised," the regulator stated.
'Potential to Erode Confidence'
The watchdog's statement declared: "The inquiry we conducted determined that the documentary's failure to disclose that the presenter's parent held a role in the Hamas-administered government was substantially inaccurate.
"Consequently that the audience did not have critical information which may have been very significant to their assessment of the narrator and the content he shared.
"Credibility is at the center of the bond between a broadcaster and its viewers, especially for a public service broadcaster such as the British Broadcasting Corporation.
"This error had the potential to erode the exceptionally strong amounts of trust that audiences would have put in a documentary produced by the BBC about the conflict in Gaza."
The programme was withdrawn from the online platform in the month of February after the presenter's familial connections emerged, and in July an internal BBC review found it breached the corporation's content policies on factual correctness.
A representative for the broadcaster said: "The Ofcom ruling is in accordance with the results of the internal assessment, that there was a major oversight in the documentary in relation to the corporation's content standards on truthfulness, which aligns with Rule 2.2 of Ofcom's Broadcasting Code.
"We issued an apology for this and we agree with the regulator's ruling in its entirety. We will adhere to the sanction as soon as the schedule and wording are determined."
