The public service broadcaster engaged in a "significant breach" of industry standards by not revealing that the voice of a programme about the Gaza conflict was the son of a Hamas representative, as ruled by British broadcasting authority Ofcom.
An investigation by the broadcasting watchdog into Gaza: How to Survive a Warzone has concluded that the film was "significantly deceptive".
The BBC's director general had already issued an apology, stating there had been "a significant failing in relation to factual correctness".
Ofcom has instructed the broadcaster to broadcast a evening announcement about its conclusions.
"Since this amounts to a significant violation of our rules, we are instructing the corporation to broadcast a message of our conclusions against it on the BBC's second channel at 9pm, with a schedule to be finalised," the regulator stated.
'Possibility to Erode Credibility'
The watchdog's report stated: "Our probe found that the documentary's failure to disclose that the narrator's father occupied a role in the Hamas-administered government was significantly deceptive.
"Consequently that the viewers did not have essential details which may have been highly relevant to their assessment of the narrator and the content he shared.
"Credibility is at the center of the relationship between a media organization and its audience, especially for a national broadcasting corporation such as the BBC.
"This oversight had the potential to erode the very considerable amounts of trust that the public would have invested in a BBC factual programme about the conflict in Gaza."
The programme was removed from iPlayer in February after the narrator's familial connections were revealed, and in July an broadcaster's internal assessment determined it violated the organization's journalistic standards on factual correctness.
A representative for the broadcaster said: "The regulator's decision is in line with the results of the internal assessment, that there was a major oversight in the film in relation to the BBC's Editorial Guidelines on factual correctness, which reflects Rule 2.2 of the regulator's media standards.
"We expressed regret for this and we accept Ofcom's decision in its entirety. We will follow the directive as soon as the date and language are finalised."
