The public service broadcaster committed a "significant breach" of media regulations by not revealing that the voice of a programme about the Gaza situation was the child of a Hamas official, as ruled by British broadcasting authority Ofcom.
An inquiry by Ofcom into Gaza: How to Survive a Warzone has determined that the documentary was "substantially inaccurate".
The BBC's director general had earlier expressed regret, stating there had been "a serious error in relation to accuracy".
The authority has instructed the BBC to broadcast a evening statement about its decisions.
"Since this amounts to a major infringement of our rules, we are instructing the BBC to air a announcement of our conclusions against it on BBC Two at 21:00, with a schedule to be finalised," the statement read.
'Potential to Erode Confidence'
The regulator's statement stated: "Our investigation concluded that the film's omission to reveal that the presenter's male guardian occupied a position in the Hamas-administered administration was significantly deceptive.
"It meant that the audience did not have essential details which may have been extremely pertinent to their assessment of the narrator and the content he provided.
"Credibility is at the heart of the bond between a television network and its audience, notably for a state-funded media outlet such as the British Broadcasting Corporation.
"This error had the potential to undermine the exceptionally strong amounts of confidence that the public would have put in a documentary produced by the BBC about the Gaza conflict."
The documentary was removed from iPlayer in last February after the boy's personal associations emerged, and in July an broadcaster's internal assessment determined it breached the organization's journalistic standards on factual correctness.
A corporation official commented: "The regulator's decision is in line with the findings of Peter Johnston's review, that there was a major oversight in the documentary in relation to the broadcaster's journalistic policies on factual correctness, which aligns with clause 2.2 of the authority's broadcasting regulations.
"We expressed regret for this and we agree with Ofcom's decision in complete. We will follow the penalty as soon as the timing and wording are finalised."
