The British broadcaster committed a "significant breach" of media regulations by not revealing that the narrator of a programme about Gaza was the son of a Hamas official, as ruled by British broadcasting authority Ofcom.
An investigation by the media regulator into Gaza: How to Survive a Warzone has found that the film was "substantially inaccurate".
The BBC's director general had already issued an apology, noting there had been "a serious error in relation to truthfulness".
Ofcom has directed the BBC to transmit a prime-time declaration about its conclusions.
"Given this constitutes a serious breach of our code, we are ordering the BBC to broadcast a message of our conclusions against it on the BBC's second channel at 21:00, with a schedule to be determined," the statement read.
'Potential to Damage Trust'
The regulator's announcement said: "Our probe concluded that the documentary's failure to disclose that the voice's male guardian served in a position in the Hamas-controlled administration was significantly deceptive.
"It meant that the audience did not have critical information which may have been very significant to their assessment of the narrator and the information he provided.
"Credibility is at the heart of the connection between a media organization and its audience, particularly for a state-funded media outlet such as the public broadcaster.
"This failing had the potential to undermine the exceptionally strong levels of confidence that audiences would have invested in a BBC factual programme about the conflict in Gaza."
The documentary was pulled from the online platform in February after the presenter's family links came to light, and in the month of July an broadcaster's internal assessment concluded it breached the organization's journalistic standards on factual correctness.
A BBC spokesperson said: "The authority's determination is in accordance with the results of the corporation's inquiry, that there was a serious error in the programme in relation to the corporation's content standards on factual correctness, which reflects regulation 2.2 of Ofcom's Broadcasting Code.
"We issued an apology for this and we accept the authority's determination in its entirety. We will adhere to the sanction as soon as the timing and language are finalised."
