The public service broadcaster engaged in a "major breach" of industry standards by omitting to mention that the presenter of a documentary about the Gaza situation was the son of a Hamas administrator, according to UK media regulator Ofcom.
An inquiry by Ofcom into the documentary titled Gaza: How to Survive a Warzone has concluded that the film was "significantly deceptive".
The BBC's director general had earlier expressed regret, noting there had been "a significant failing in relation to accuracy".
The regulator has directed the broadcaster to air a peak-time declaration about its conclusions.
"Since this amounts to a serious breach of our code, we are ordering the corporation to broadcast a message of our determinations against it on BBC2 at 21:00, with a schedule to be determined," it said.
'Risk to Erode Confidence'
The authority's announcement declared: "The inquiry we conducted found that the programme's lack of disclosure that the presenter's male guardian occupied a post in the Hamas-administered administration was materially misleading.
"It meant that the public did not have essential details which may have been extremely pertinent to their judgment of the voice and the details he presented.
"Trust is at the core of the relationship between a television network and its viewers, notably for a public service broadcaster such as the British Broadcasting Corporation.
"This failing had the possibility to undermine the significantly high degrees of credibility that the public would have put in a documentary produced by the BBC about the Gaza conflict."
The programme was pulled from the online platform in last February after the narrator's personal associations were revealed, and in July an broadcaster's internal assessment determined it violated the corporation's journalistic standards on truthfulness.
A corporation official said: "The regulator's decision is in line with the findings of the corporation's inquiry, that there was a significant failing in the film in relation to the broadcaster's journalistic policies on truthfulness, which reflects clause 2.2 of the regulator's media standards.
"We issued an apology 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."
