The British broadcaster engaged in a "significant breach" of broadcasting rules by failing to disclose that the narrator of a film about Gaza was the son of a Hamas administrator, as ruled by UK media regulator Ofcom.
An investigation by Ofcom into the programme Gaza: How to Survive a Warzone has concluded that the film was "substantially inaccurate".
The chief executive of the broadcaster had previously apologised, stating there had been "a major oversight in relation to truthfulness".
The regulator has ordered the BBC to air a peak-time declaration about its conclusions.
"As this represents a significant violation of our code, we are instructing the corporation to transmit a message of our determinations against it on BBC Two at nine o'clock in the evening, with a date to be confirmed," it said.
'Potential to Erode Credibility'
The authority's report stated: "Our investigation found that the film's omission to reveal that the narrator's male guardian occupied a post in the Hamas-run government was materially misleading.
"It meant that the viewers did not have critical information which may have been highly relevant to their evaluation of the presenter and the content he provided.
"Confidence is at the core of the bond between a broadcaster and its viewers, especially for a state-funded media outlet such as the BBC.
"This oversight had the risk to damage the significantly high levels of confidence that the public would have placed in a documentary produced by the BBC about the Israel-Gaza war."
The documentary was withdrawn from the BBC's streaming service in last February after the narrator's familial connections came to light, and in July an corporation's own inquiry concluded it breached the broadcaster's journalistic standards on accuracy.
A corporation official stated: "The authority's determination is in accordance with the conclusions of the internal assessment, that there was a major oversight in the documentary in relation to the corporation's content standards on factual correctness, which corresponds to regulation 2.2 of the authority's broadcasting regulations.
"We issued an apology for this and we comply with the regulator's ruling in full. We will comply with the penalty as soon as the date and wording are finalised."
