The public service broadcaster committed a "major breach" of media regulations by not revealing that the voice of a programme about the Gaza conflict was the offspring of a Hamas representative, according to regulatory body Ofcom.
An inquiry by the media regulator into Gaza: How to Survive a Warzone has determined that the documentary was "substantially inaccurate".
The head of the BBC had already issued an apology, noting there had been "a major oversight in relation to accuracy".
Ofcom has instructed the broadcaster to broadcast a evening declaration about its decisions.
"Since this amounts to a major infringement of our rules, we are directing the corporation to air a message of our conclusions against it on BBC Two at nine o'clock in the evening, with a timing to be finalised," the regulator stated.
'Potential to Erode Credibility'
The authority's report said: "The inquiry we conducted concluded that the film's lack of disclosure that the voice's father occupied a role in the Hamas-run government was significantly deceptive.
"This implied that the audience did not have critical information which may have been extremely pertinent to their evaluation of the voice and the information he shared.
"Credibility is at the center of the relationship between a broadcaster and its viewers, particularly for a state-funded media outlet such as the public broadcaster.
"This oversight had the possibility to undermine the exceptionally strong degrees of credibility that audiences would have invested in a factual film from the broadcaster about the Israel-Gaza war."
The documentary was pulled from iPlayer in last February after the presenter's familial connections came to light, and in the month of July an internal BBC review determined it violated the organization's journalistic standards on truthfulness.
A BBC spokesperson stated: "The authority's determination is in line with the findings of Peter Johnston's review, that there was a major oversight in the programme in relation to the corporation's content standards on factual correctness, which reflects clause 2.2 of Ofcom's Broadcasting Code.
"We issued an apology for this and we comply with Ofcom's decision in full. We will adhere to the penalty as soon as the date and language are confirmed."
