The British broadcaster engaged in a "significant breach" of media regulations by failing to disclose that the narrator of a film about the Gaza situation 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 "significantly deceptive".
The BBC's director general had already issued an apology, saying there had been "a serious error in relation to truthfulness".
Ofcom has instructed the corporation to air a evening declaration about its findings.
"Given this constitutes a major infringement of our code, we are instructing the corporation to broadcast a statement of our determinations against it on BBC2 at 21:00, with a timing to be finalised," the regulator stated.
'Potential to Erode Credibility'
The authority's report declared: "The inquiry we conducted concluded that the film's lack of disclosure that the voice's male guardian served in a position in the Hamas-run authority was significantly deceptive.
"This implied that the public did not have critical information which may have been very significant to their assessment of the narrator and the content he presented.
"Confidence is at the core of the bond between a broadcaster and its viewers, particularly for a state-funded media outlet such as the BBC.
"This oversight had the possibility to undermine the exceptionally strong amounts of credibility that the public would have invested in a BBC factual programme about the Gaza conflict."
The programme was withdrawn from the BBC's streaming service in February after the narrator's family links came to light, and in July an corporation's own inquiry found it breached the corporation's editorial guidelines on factual correctness.
A corporation official stated: "The authority's determination is in agreement with the findings of the internal assessment, that there was a significant failing in the programme in relation to the corporation's content standards on accuracy, which aligns with clause 2.2 of the regulator's media standards.
"We expressed regret for this and we agree with the regulator's ruling in full. We will adhere to the penalty as soon as the timing and language are confirmed."
