The BBC committed a "major breach" of broadcasting rules by failing to disclose that the voice of a programme about the Gaza conflict was the offspring of a Hamas administrator, as determined by regulatory body Ofcom.
An probe by Ofcom into the programme Gaza: How to Survive a Warzone has determined that the documentary was "materially misleading".
The head of the BBC had already issued an apology, saying there had been "a significant failing in relation to truthfulness".
Ofcom has instructed the BBC to air a prime-time declaration about its decisions.
"As this represents a major infringement of our code, we are directing the corporation to transmit a message of our determinations against it on BBC2 at nine o'clock in the evening, with a schedule to be determined," the regulator stated.
'Potential to Undermine Confidence'
The authority's statement said: "The inquiry we conducted determined that the programme's omission to reveal that the presenter's male guardian served in a position in the Hamas-controlled authority was significantly deceptive.
"Consequently that the public did not have essential details which may have been highly relevant to their judgment of the presenter and the information he provided.
"Credibility is at the heart of the connection between a media organization and its viewers, especially for a national broadcasting corporation such as the BBC.
"This oversight had the possibility to erode the significantly high degrees of credibility that audiences would have placed in a documentary produced by the BBC about the conflict in Gaza."
The film was pulled from the online platform in February after the narrator's family links came to light, and in the month of July an broadcaster's internal assessment determined it breached the corporation's editorial guidelines on accuracy.
A corporation official stated: "The regulator's decision is in accordance with the findings of Peter Johnston's review, that there was a serious error in the programme in relation to the corporation's content standards on truthfulness, which reflects clause 2.2 of the regulator's media standards.
"We expressed regret for this and we accept the authority's determination in its entirety. We will follow the penalty as soon as the timing and wording are finalised."
