The British broadcaster committed a "major breach" of industry standards by not revealing that the voice of a film about Gaza was the child of a Hamas official, as ruled by UK media regulator Ofcom.
An investigation by Ofcom into Gaza: How to Survive a Warzone has concluded 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 regulator has directed the broadcaster to air a peak-time declaration about its decisions.
"As this represents a major infringement of our regulations, we are instructing the corporation to air a message of our findings against it on BBC2 at nine o'clock in the evening, with a timing to be confirmed," the statement read.
'Risk to Erode Trust'
The regulator's announcement said: "Our probe concluded that the documentary's failure to disclose that the narrator's parent served in a post in the Hamas-run administration was significantly deceptive.
"It meant that the viewers did not have essential details which may have been extremely pertinent to their assessment of the presenter and the information he shared.
"Credibility is at the core of the connection between a broadcaster and its audience, notably for a state-funded media outlet such as the BBC.
"This oversight had the possibility to erode the very considerable levels of confidence that audiences would have placed in a BBC factual programme about the Israel-Gaza war."
The documentary was withdrawn from the BBC's streaming service in February after the boy's personal associations came to light, and in this past July an internal BBC review determined it breached the organization's journalistic standards on factual correctness.
A corporation official stated: "The Ofcom ruling is in accordance with the results of the corporation's inquiry, that there was a significant failing in the film in relation to the BBC's Editorial Guidelines on truthfulness, which aligns with Rule 2.2 of the authority's broadcasting regulations.
"We issued an apology for this and we accept Ofcom's decision in full. We will comply with the directive as soon as the date and wording are finalised."
