The BBC committed a "significant breach" of industry standards by not revealing that the voice of a film about the Gaza conflict was the child of a Hamas representative, according to regulatory body Ofcom.
An investigation by the broadcasting watchdog into Gaza: How to Survive a Warzone has found that the film was "materially misleading".
The chief executive of the broadcaster had already issued an apology, noting there had been "a serious error in relation to factual correctness".
The authority has ordered the broadcaster to air a prime-time announcement about its findings.
"Given this constitutes a major infringement of our code, we are directing the broadcaster to air a announcement of our conclusions against it on the BBC's second channel at 9pm, with a date to be determined," it said.
'Potential to Damage Trust'
The regulator's statement stated: "Our investigation concluded that the film's lack of disclosure that the narrator's male guardian occupied a post in the Hamas-controlled administration was significantly deceptive.
"Consequently that the public did not have vital facts which may have been extremely pertinent to their judgment of the presenter and the content he shared.
"Confidence is at the heart of the bond 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 significantly high degrees of confidence that viewers would have invested in a documentary produced by the BBC about the Gaza conflict."
The programme was withdrawn from iPlayer in the month of February after the narrator's familial connections came to light, and in this past July an broadcaster's internal assessment determined it violated the corporation's content policies on truthfulness.
A BBC spokesperson said: "The regulator's decision is in line with the conclusions of the corporation's inquiry, that there was a significant failing in the programme in relation to the broadcaster's journalistic policies on truthfulness, which reflects Rule 2.2 of Ofcom's Broadcasting Code.
"We have apologised for this and we comply with the regulator's ruling in its entirety. We will comply with the penalty as soon as the schedule and language are finalised."
