The public service broadcaster committed a "significant breach" of media regulations by omitting to mention that the narrator of a programme about Gaza was the child of a Hamas administrator, according to regulatory body Ofcom.
An investigation by the media regulator into the documentary titled Gaza: How to Survive a Warzone has found that the programme was "materially misleading".
The BBC's director general had already issued an apology, saying there had been "a significant failing in relation to factual correctness".
Ofcom has instructed the BBC to broadcast a peak-time announcement about its decisions.
"Since this amounts to a significant violation of our rules, we are instructing the BBC to broadcast a statement of our determinations against it on the BBC's second channel at 21:00, with a date to be finalised," the regulator stated.
'Potential to Undermine Credibility'
The regulator's announcement declared: "The inquiry we conducted determined that the programme's lack of disclosure that the narrator's parent served in a post in the Hamas-run administration was materially misleading.
"It meant that the audience did not have essential details which may have been extremely pertinent to their judgment of the voice and the information he provided.
"Confidence is at the heart of the relationship between a media organization and its public, notably for a state-funded media outlet such as the public broadcaster.
"This error had the potential to undermine the exceptionally strong degrees of trust that audiences would have placed in a BBC factual programme about the Gaza conflict."
The documentary was removed from the BBC's streaming service in last February after the presenter's family links were revealed, and in July an broadcaster's internal assessment determined it infringed the broadcaster's content policies on truthfulness.
A corporation official commented: "The Ofcom ruling is in agreement with the findings of the internal assessment, that there was a major oversight in the programme 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 Ofcom's decision in full. We will comply with the penalty as soon as the schedule and wording are determined."
