The BBC was found to have committed a "serious breach" of media regulations by not revealing that the narrator of a programme about the Gaza situation was the child of a Hamas official, as determined by UK media regulator Ofcom.
An investigation by the media regulator into Gaza: How to Survive a Warzone has found that the documentary was "materially misleading".
The head of the BBC had earlier expressed regret, noting there had been "a major oversight in relation to accuracy".
Ofcom has ordered the corporation to air a prime-time declaration about its findings.
"Since this amounts to a major infringement of our rules, we are directing the corporation to air a message of our conclusions against it on BBC2 at nine o'clock in the evening, with a timing to be determined," it said.
'Potential to Erode Confidence'
The watchdog's report said: "Our investigation found that the documentary's omission to reveal that the voice's father served in a position in the Hamas-administered authority was materially misleading.
"Consequently that the public did not have essential details which may have been extremely pertinent to their evaluation of the voice and the details he provided.
"Confidence is at the heart of the bond between a media organization and its viewers, notably for a public service broadcaster such as the public broadcaster.
"This oversight had the potential to erode the very considerable levels of confidence that audiences would have put in a factual film from the broadcaster about the conflict in Gaza."
The film was removed from iPlayer in February after the presenter's family links emerged, and in July an broadcaster's internal assessment found it breached the corporation's journalistic standards on accuracy.
A corporation official commented: "The regulator's decision is in line with the conclusions of the internal assessment, that there was a significant failing in the film in relation to the broadcaster's journalistic policies on truthfulness, which aligns with regulation 2.2 of Ofcom's Broadcasting Code.
"We issued an apology for this and we comply with the regulator's ruling in full. We will adhere to the directive as soon as the schedule and wording are determined."
