The BBC committed a "major breach" of broadcasting rules by omitting to mention that the voice of a programme about the Gaza conflict was the child of a Hamas representative, according to regulatory body Ofcom.
An probe by Ofcom into Gaza: How to Survive a Warzone has determined that the programme was "significantly deceptive".
The head of the BBC had previously apologised, saying there had been "a significant failing in relation to accuracy".
The authority has ordered the BBC to broadcast a prime-time declaration about its conclusions.
"Since this amounts to a significant violation of our code, we are instructing the broadcaster to air a announcement of our findings against it on BBC Two at 21:00, with a date to be confirmed," it said.
'Risk to Damage Credibility'
The regulator's statement declared: "Our investigation determined that the documentary's failure to disclose that the narrator's male guardian occupied a post in the Hamas-administered government was substantially inaccurate.
"This implied that the audience did not have vital facts which may have been very significant to their judgment of the narrator and the content he shared.
"Credibility is at the core of the connection between a media organization and its public, notably for a national broadcasting corporation such as the public broadcaster.
"This failing had the risk to erode the very considerable degrees of trust that audiences would have placed in a documentary produced by the BBC about the Israel-Gaza war."
The film was removed from the BBC's streaming service in the month of February after the narrator's personal associations came to light, and in the month of July an broadcaster's internal assessment found it infringed the broadcaster's editorial guidelines on accuracy.
A BBC spokesperson stated: "The Ofcom ruling 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 accuracy, which aligns with Rule 2.2 of Ofcom's Broadcasting Code.
"We expressed regret for this and we accept the regulator's ruling in its entirety. We will adhere to the sanction as soon as the timing and language are confirmed."
