The British broadcaster engaged in a "significant breach" of industry standards by failing to disclose that the voice of a film about Gaza was the son of a Hamas official, as ruled by regulatory body Ofcom.
An probe by the broadcasting watchdog into Gaza: How to Survive a Warzone has determined that the documentary was "substantially inaccurate".
The BBC's director general had already issued an apology, saying there had been "a major oversight in relation to accuracy".
Ofcom has directed the BBC to air a prime-time declaration about its conclusions.
"Given this constitutes a major infringement of our rules, we are instructing the broadcaster to air a statement of our determinations against it on the BBC's second channel at 9pm, with a schedule to be confirmed," it said.
'Potential to Erode Trust'
The regulator's announcement said: "The inquiry we conducted found that the documentary's omission to reveal that the presenter's parent served in a role in the Hamas-administered authority was materially misleading.
"This implied that the audience did not have critical information which may have been extremely pertinent to their judgment of the voice and the content he provided.
"Credibility is at the heart of the relationship between a broadcaster and its audience, especially for a national broadcasting corporation such as the BBC.
"This oversight had the possibility to erode the very considerable levels of credibility that the public would have put in a documentary produced by the BBC about the Israel-Gaza war."
The documentary was pulled from the online platform in last February after the boy's familial connections were revealed, and in the month of July an broadcaster's internal assessment concluded it violated the broadcaster's journalistic standards on factual correctness.
A BBC spokesperson said: "The regulator's decision is in line with the findings of the corporation's inquiry, that there was a serious error in the film in relation to the corporation's content standards on factual correctness, which corresponds to regulation 2.2 of the authority's broadcasting regulations.
"We have apologised for this and we accept the authority's determination in full. We will comply with the sanction as soon as the schedule and wording are determined."
