The public service broadcaster engaged in a "serious breach" of broadcasting rules by not revealing that the voice of a film about the Gaza situation was the offspring of a Hamas official, as determined by British broadcasting authority Ofcom.
An inquiry by the media regulator into the documentary titled Gaza: How to Survive a Warzone has determined that the documentary was "materially misleading".
The BBC's director general had earlier expressed regret, saying there had been "a significant failing in relation to truthfulness".
The authority has directed the corporation to broadcast a peak-time announcement about its conclusions.
"Since this amounts to a serious breach of our regulations, we are instructing the BBC to air a message of our conclusions against it on BBC2 at nine o'clock in the evening, with a schedule to be confirmed," the statement read.
'Possibility to Damage Trust'
The authority's statement said: "Our investigation found that the film's omission to reveal that the narrator's parent served in a role in the Hamas-administered authority was significantly deceptive.
"Consequently that the public did not have critical information which may have been very significant to their assessment of the narrator and the information he presented.
"Trust is at the core of the relationship between a television network and its public, particularly for a state-funded media outlet such as the BBC.
"This oversight had the potential to erode the significantly high levels of confidence that the public would have placed in a BBC factual programme about the conflict in Gaza."
The programme was pulled from the BBC's streaming service in February after the presenter's family links emerged, and in this past July an internal BBC review found it infringed the broadcaster's journalistic standards on factual correctness.
A representative for the broadcaster stated: "The authority's determination is in accordance with the findings of Peter Johnston's review, that there was a serious error in the film in relation to the corporation's content standards on truthfulness, which aligns with Rule 2.2 of the regulator's media standards.
"We have apologised for this and we agree with the authority's determination in full. We will adhere to the penalty as soon as the date and wording are determined."
