The British broadcaster committed a "significant breach" of industry standards by omitting to mention that the voice of a film about Gaza was the son of a Hamas official, according to regulatory body Ofcom.
An inquiry by the broadcasting watchdog into Gaza: How to Survive a Warzone has concluded that the documentary was "significantly deceptive".
The head of the BBC had already issued an apology, noting there had been "a significant failing in relation to accuracy".
Ofcom has ordered the corporation to air a evening declaration about its findings.
"As this represents a significant violation of our rules, we are instructing the corporation to broadcast a announcement of our findings against it on BBC2 at 21:00, with a timing to be finalised," the regulator stated.
'Possibility to Damage Trust'
The regulator's statement stated: "The inquiry we conducted determined that the film's lack of disclosure that the presenter's male guardian served in a post in the Hamas-controlled authority was substantially inaccurate.
"Consequently that the audience did not have essential details which may have been extremely pertinent to their evaluation of the presenter and the content he shared.
"Credibility is at the heart of the connection between a television network and its audience, especially for a state-funded media outlet such as the BBC.
"This oversight had the potential to damage the very considerable levels of trust that audiences would have put in a BBC factual programme about the conflict in Gaza."
The documentary was removed from the BBC's streaming service in last February after the boy's personal associations came to light, and in the month of July an internal BBC review determined it violated the broadcaster's journalistic standards on truthfulness.
A BBC spokesperson said: "The authority's determination is in accordance with the conclusions of the corporation's inquiry, that there was a significant failing in the documentary in relation to the BBC's Editorial Guidelines on accuracy, which aligns with regulation 2.2 of Ofcom's Broadcasting Code.
"We have apologised for this and we comply with the regulator's ruling in complete. We will adhere to the sanction as soon as the date and language are determined."
