The BBC was found to have committed a "major breach" of broadcasting rules by omitting to mention that the voice of a programme about the Gaza situation was the offspring of a Hamas administrator, as ruled by UK media regulator Ofcom.
An investigation by the media regulator into the programme Gaza: How to Survive a Warzone has found that the documentary was "significantly deceptive".
The chief executive of the broadcaster had already issued an apology, stating there had been "a major oversight in relation to accuracy".
The authority has ordered the BBC to air a peak-time declaration about its findings.
"As this represents a serious breach of our code, we are instructing the BBC to air a statement of our conclusions against it on the BBC's second channel at nine o'clock in the evening, with a schedule to be finalised," the statement read.
'Potential to Undermine Trust'
The regulator's statement said: "Our investigation found that the documentary's failure to disclose that the narrator's male guardian held a post in the Hamas-run authority was materially misleading.
"This implied that the public did not have vital facts which may have been highly relevant to their judgment of the presenter and the content he presented.
"Trust is at the center of the connection between a television network and its audience, especially for a national broadcasting corporation such as the British Broadcasting Corporation.
"This failing had the risk to undermine the significantly high degrees of credibility that the public would have invested in a BBC factual programme about the Israel-Gaza war."
The documentary was pulled from the BBC's streaming service in February after the narrator's family links came to light, and in July an corporation's own inquiry determined it infringed the broadcaster's journalistic standards on accuracy.
A BBC spokesperson commented: "The Ofcom ruling is in accordance with the findings of the corporation's inquiry, that there was a serious error in the film in relation to the broadcaster's journalistic policies on factual correctness, which reflects clause 2.2 of Ofcom's Broadcasting Code.
"We issued an apology for this and we agree with the authority's determination in full. We will comply with the penalty as soon as the schedule and wording are finalised."
