The public service broadcaster engaged in a "significant breach" of industry standards by omitting to mention that the voice of a documentary about Gaza was the son of a Hamas administrator, according to British broadcasting authority Ofcom.
An inquiry by the broadcasting watchdog into Gaza: How to Survive a Warzone has determined that the film was "materially misleading".
The BBC's director general had previously apologised, noting there had been "a major oversight in relation to accuracy".
The regulator has directed the BBC to air a evening announcement about its findings.
"Since this amounts to a significant violation of our code, we are directing the BBC to transmit a statement of our findings against it on BBC Two at 21:00, with a timing to be determined," the statement read.
'Possibility to Damage Credibility'
The watchdog's statement stated: "The inquiry we conducted found that the documentary's lack of disclosure that the voice's parent occupied a position in the Hamas-controlled administration was materially misleading.
"It meant that the audience did not have vital facts which may have been extremely pertinent to their evaluation of the presenter and the content he shared.
"Confidence is at the heart of the bond between a television network and its viewers, notably for a national broadcasting corporation such as the BBC.
"This error had the risk to erode the very considerable amounts of credibility that the public would have put in a BBC factual programme about the Israel-Gaza war."
The documentary was withdrawn from the BBC's streaming service in last February after the presenter's personal associations emerged, and in July an broadcaster's internal assessment found it infringed the corporation's editorial guidelines on factual correctness.
A representative for the broadcaster said: "The authority's determination is in agreement with the findings of the corporation's inquiry, that there was a serious error in the documentary in relation to the broadcaster's journalistic policies on accuracy, which corresponds to Rule 2.2 of the regulator's media standards.
"We have apologised for this and we agree with the regulator's ruling in full. We will adhere to the penalty as soon as the timing and wording are finalised."
