The British broadcaster engaged in a "serious breach" of media regulations by not revealing that the voice of a film about Gaza was the son of a Hamas representative, as ruled by UK media regulator Ofcom.
An inquiry by the broadcasting watchdog into the programme Gaza: How to Survive a Warzone has determined that the film was "significantly deceptive".
The chief executive of the broadcaster had earlier expressed regret, noting there had been "a serious error in relation to accuracy".
Ofcom has ordered the broadcaster to transmit a peak-time declaration about its decisions.
"Given this constitutes a significant violation of our rules, we are directing the broadcaster to transmit a message of our findings against it on the BBC's second channel at 21:00, with a date to be confirmed," it said.
'Risk to Erode Confidence'
The authority's report said: "Our probe found that the documentary's failure to disclose that the voice's male guardian occupied a position in the Hamas-administered administration was materially misleading.
"Consequently that the viewers did not have vital facts which may have been highly relevant to their judgment of the voice and the details he provided.
"Confidence is at the core of the connection between a broadcaster and its viewers, notably for a national broadcasting corporation such as the British Broadcasting Corporation.
"This failing had the potential to undermine the exceptionally strong levels of confidence that viewers would have placed in a BBC factual programme about the Israel-Gaza war."
The film was removed from the online platform in February after the narrator's personal associations emerged, and in this past July an corporation's own inquiry concluded it breached the broadcaster's journalistic standards on factual correctness.
A representative for the broadcaster said: "The authority's determination is in agreement with the results of Peter Johnston's review, that there was a serious error in the programme in relation to the BBC's Editorial Guidelines on truthfulness, which corresponds to Rule 2.2 of the authority's broadcasting regulations.
"We issued an apology for this and we accept the regulator's ruling in its entirety. We will adhere to the sanction as soon as the date and language are determined."
