The public service broadcaster committed a "major breach" of industry standards by not revealing that the presenter of a programme about Gaza was the offspring of a Hamas official, as ruled by regulatory body Ofcom.
An inquiry by Ofcom into Gaza: How to Survive a Warzone has found that the film was "materially misleading".
The BBC's director general had already issued an apology, saying there had been "a significant failing in relation to truthfulness".
Ofcom has instructed the corporation to air a peak-time announcement about its conclusions.
"Given this constitutes a serious breach of our regulations, we are ordering the broadcaster to transmit a announcement of our conclusions against it on the BBC's second channel at 21:00, with a timing to be finalised," the regulator stated.
'Risk to Damage Credibility'
The regulator's statement said: "Our probe found that the film's omission to reveal that the narrator's father held a position in the Hamas-run authority was significantly deceptive.
"Consequently that the public did not have vital facts which may have been highly relevant to their assessment of the presenter and the content he provided.
"Credibility is at the heart of the relationship between a television network and its viewers, especially for a state-funded media outlet such as the public broadcaster.
"This oversight had the risk to undermine the very considerable amounts of trust that audiences would have placed in a documentary produced by the BBC about the Israel-Gaza war."
The film was removed from the online platform in last February after the narrator's familial connections came to light, and in the month of July an corporation's own inquiry found it infringed the broadcaster's journalistic standards on accuracy.
A corporation official said: "The Ofcom ruling is in agreement with the conclusions of the corporation's inquiry, that there was a serious error in the documentary in relation to the broadcaster's journalistic policies on factual correctness, which corresponds to Rule 2.2 of Ofcom's Broadcasting Code.
"We issued an apology for this and we comply with the authority's determination in full. We will follow the penalty as soon as the timing and wording are confirmed."
