The BBC was found to have committed a "significant breach" of industry standards by failing to disclose that the voice of a programme about the Gaza situation was the offspring of a Hamas official, as determined by British broadcasting authority Ofcom.
An investigation by Ofcom into Gaza: How to Survive a Warzone has concluded that the film was "substantially inaccurate".
The BBC's director general had previously apologised, noting there had been "a major oversight in relation to factual correctness".
The authority has ordered the BBC to transmit a prime-time announcement about its conclusions.
"As this represents a major infringement of our rules, we are directing the BBC to broadcast a message of our conclusions against it on BBC Two at 21:00, with a schedule to be confirmed," it said.
'Possibility to Damage Credibility'
The authority's announcement stated: "The inquiry we conducted found that the documentary's failure to disclose that the presenter's male guardian served in a post in the Hamas-administered administration was significantly deceptive.
"It meant that the viewers did not have critical information which may have been highly relevant to their evaluation of the presenter and the details he presented.
"Credibility is at the core of the bond between a media organization and its audience, particularly for a national broadcasting corporation such as the BBC.
"This error had the risk to undermine the significantly high degrees of confidence that audiences would have put in a factual film from the broadcaster about the Gaza conflict."
The documentary was withdrawn from the BBC's streaming service in the month of February after the narrator's familial connections emerged, and in July an broadcaster's internal assessment determined it infringed the organization's editorial guidelines on factual correctness.
A representative for the broadcaster stated: "The authority's determination is in line with the conclusions of the internal assessment, that there was a significant failing in the documentary in relation to the broadcaster's journalistic policies on truthfulness, which corresponds to Rule 2.2 of the regulator's media standards.
"We issued an apology for this and we agree with the regulator's ruling in complete. We will comply with the penalty as soon as the timing and wording are confirmed."
