The BBC engaged in a "serious breach" of industry standards by not revealing that the presenter of a programme about Gaza was the son of a Hamas official, as determined by British broadcasting authority Ofcom.
An inquiry by the broadcasting watchdog into Gaza: How to Survive a Warzone has determined that the film was "materially misleading".
The chief executive of the broadcaster had already issued an apology, saying there had been "a significant failing in relation to truthfulness".
Ofcom has ordered the broadcaster to air a prime-time announcement about its conclusions.
"Since this amounts to a significant violation of our rules, we are directing the broadcaster to broadcast a statement of our determinations against it on BBC2 at 9pm, with a timing to be finalised," the statement read.
'Possibility to Erode Credibility'
The watchdog's statement said: "The inquiry we conducted found that the documentary's omission to reveal that the narrator's male guardian served in a post in the Hamas-run government was significantly deceptive.
"This implied that the audience did not have critical information which may have been highly relevant to their judgment of the presenter and the information he shared.
"Trust is at the core of the relationship between a media organization and its audience, especially for a national broadcasting corporation such as the British Broadcasting Corporation.
"This failing had the risk to undermine the exceptionally strong degrees of credibility that viewers would have put in a factual film from the broadcaster about the conflict in Gaza."
The programme was pulled from the BBC's streaming service in February after the presenter's personal associations came to light, and in this past July an broadcaster's internal assessment found it breached the broadcaster's content policies on accuracy.
A representative for the broadcaster commented: "The regulator's decision is in agreement with the findings of the corporation's inquiry, that there was a serious error in the documentary in relation to the BBC's Editorial Guidelines on accuracy, which reflects Rule 2.2 of Ofcom's Broadcasting Code.
"We issued an apology for this and we accept the regulator's ruling in its entirety. We will adhere to the penalty as soon as the date and language are confirmed."
