The public service broadcaster engaged in a "significant breach" of broadcasting rules by not revealing that the narrator of a film about Gaza was the son of a Hamas official, as determined by regulatory body Ofcom.
An inquiry by Ofcom into Gaza: How to Survive a Warzone has concluded that the film was "substantially inaccurate".
The chief executive of the broadcaster had already issued an apology, noting there had been "a major oversight in relation to accuracy".
Ofcom has instructed the corporation to air a prime-time declaration about its decisions.
"As this represents a serious breach of our regulations, we are ordering the BBC to transmit a message of our findings against it on BBC Two at 9pm, with a date to be determined," the regulator stated.
'Risk to Undermine Confidence'
The authority's announcement stated: "Our probe concluded that the programme's lack of disclosure that the narrator's father served in a post in the Hamas-controlled administration was significantly deceptive.
"This implied that the public did not have critical information which may have been highly relevant to their evaluation of the presenter and the content he presented.
"Confidence is at the heart of the connection between a broadcaster and its viewers, particularly for a national broadcasting corporation such as the BBC.
"This error had the possibility to erode the exceptionally strong amounts of trust that audiences would have put in a factual film from the broadcaster about the conflict in Gaza."
The documentary was removed from the BBC's streaming service in the month of February after the presenter's familial connections emerged, and in this past July an broadcaster's internal assessment determined it infringed the organization's editorial guidelines on truthfulness.
A BBC spokesperson said: "The authority's determination is in agreement with the conclusions of Peter Johnston's review, that there was a serious error in the programme in relation to the broadcaster's journalistic policies on accuracy, which corresponds to 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 adhere to the penalty as soon as the date and language are confirmed."
