The BBC was found to have committed a "major breach" of media regulations by not revealing that the voice of a documentary about the Gaza situation was the child of a Hamas administrator, as ruled by British broadcasting authority Ofcom.
An probe by the media regulator into Gaza: How to Survive a Warzone has concluded that the documentary was "significantly deceptive".
The BBC's director general had previously apologised, saying there had been "a significant failing in relation to truthfulness".
Ofcom has directed the BBC to transmit a evening declaration about its conclusions.
"Given this constitutes a major infringement of our code, we are instructing the corporation to air a statement of our findings against it on the BBC's second channel at 9pm, with a timing to be determined," it said.
'Potential to Damage Trust'
The watchdog's statement said: "Our probe found that the film's omission to reveal that the voice's parent held a post in the Hamas-administered administration was substantially inaccurate.
"Consequently that the viewers did not have essential details which may have been highly relevant to their judgment of the narrator and the information he presented.
"Credibility is at the center of the connection between a media organization and its public, especially for a state-funded media outlet such as the public broadcaster.
"This error had the risk to undermine the very considerable degrees of trust that audiences would have invested in a factual film from the broadcaster about the conflict in Gaza."
The film was removed from the BBC's streaming service in the month of February after the boy's familial connections came to light, and in this past July an internal BBC review determined it breached the corporation's editorial guidelines on factual correctness.
A BBC spokesperson commented: "The regulator's decision is in agreement with the findings of Peter Johnston's review, that there was a serious error in the documentary in relation to the corporation's content standards on accuracy, which aligns with clause 2.2 of Ofcom's Broadcasting Code.
"We expressed regret for this and we accept the authority's determination in its entirety. We will follow the sanction as soon as the date and wording are determined."
