The BBC engaged in a "major breach" of industry standards by omitting to mention that the voice of a film about the Gaza conflict was the son of a Hamas official, as ruled by British broadcasting authority Ofcom.
An investigation by Ofcom into Gaza: How to Survive a Warzone has concluded that the documentary was "substantially inaccurate".
The chief executive of the broadcaster had previously apologised, saying there had been "a serious error in relation to accuracy".
The authority has directed the broadcaster to transmit a prime-time declaration about its decisions.
"Since this amounts to a significant violation of our rules, we are directing the corporation to transmit a message of our conclusions against it on BBC2 at 9pm, with a schedule to be confirmed," it said.
'Possibility to Erode Trust'
The watchdog's report declared: "Our investigation determined that the film's failure to disclose that the narrator's father occupied a position in the Hamas-controlled administration was materially misleading.
"Consequently that the audience did not have critical information which may have been extremely pertinent to their judgment of the voice and the content he presented.
"Confidence is at the center of the relationship between a broadcaster and its viewers, notably for a public service broadcaster such as the BBC.
"This oversight had the potential to undermine the significantly high degrees of confidence that audiences would have put in a documentary produced by the BBC about the Israel-Gaza war."
The documentary was removed from the online platform in the month of February after the narrator's familial connections were revealed, and in the month of July an internal BBC review found it breached the broadcaster's editorial guidelines on factual correctness.
A BBC spokesperson said: "The Ofcom ruling is in agreement with the findings of the internal assessment, that there was a serious error in the programme in relation to the corporation's content standards on factual correctness, which aligns with Rule 2.2 of the regulator's media standards.
"We have apologised for this and we comply with the authority's determination in full. We will adhere to the directive as soon as the schedule and wording are determined."
