The BBC engaged in a "major breach" of industry standards by omitting to mention that the voice of a programme about Gaza was the offspring of a Hamas representative, according to UK media regulator Ofcom.
An probe by the media regulator into Gaza: How to Survive a Warzone has determined that the film was "materially misleading".
The chief executive of the broadcaster had earlier expressed regret, noting there had been "a significant failing in relation to factual correctness".
The authority has ordered the broadcaster to air a evening statement about its conclusions.
"Given this constitutes a major infringement of our rules, we are directing the corporation to broadcast a message of our determinations against it on BBC Two at 21:00, with a timing to be finalised," the statement read.
'Potential to Erode Trust'
The authority's statement declared: "Our probe concluded that the film's failure to disclose that the presenter's male guardian held a position in the Hamas-run administration was substantially inaccurate.
"It meant that the viewers did not have essential details which may have been very significant to their judgment of the narrator and the content he presented.
"Trust is at the heart of the relationship between a television network and its public, especially for a state-funded media outlet such as the British Broadcasting Corporation.
"This failing had the possibility to damage the very considerable amounts of confidence that the public would have placed in a BBC factual programme about the conflict in Gaza."
The programme was pulled from the online platform in last February after the narrator's family links came to light, and in July an broadcaster's internal assessment found it breached the broadcaster's content policies on accuracy.
A corporation official commented: "The regulator's decision is in line with the findings of the corporation's inquiry, that there was a major oversight in the documentary in relation to the broadcaster's journalistic policies on truthfulness, which aligns with Rule 2.2 of the authority's broadcasting regulations.
"We expressed regret for this and we accept Ofcom's decision in full. We will adhere to the penalty as soon as the date and language are confirmed."
