The BBC committed a "serious breach" of broadcasting rules by omitting to mention that the voice of a film about Gaza was the son of a Hamas representative, according to regulatory body Ofcom.
An inquiry by the media regulator into Gaza: How to Survive a Warzone has determined that the programme was "significantly deceptive".
The BBC's director general had already issued an apology, noting there had been "a major oversight in relation to factual correctness".
The authority has directed the corporation to transmit a peak-time announcement about its decisions.
"Given this constitutes a serious breach of our rules, we are instructing the BBC to air a message of our findings against it on the BBC's second channel at nine o'clock in the evening, with a date to be finalised," it said.
'Possibility to Undermine Credibility'
The regulator's report stated: "Our probe concluded that the programme's lack of disclosure that the voice's parent served in a role in the Hamas-administered government was materially misleading.
"This implied that the public did not have essential details which may have been highly relevant to their judgment of the voice and the details he provided.
"Trust is at the center of the bond between a television network and its viewers, especially for a public service broadcaster such as the BBC.
"This error had the potential to undermine the very considerable amounts of confidence that the public would have put in a factual film from the broadcaster about the conflict in Gaza."
The documentary was pulled from iPlayer in the month of February after the narrator's family links were revealed, and in this past July an broadcaster's internal assessment found it infringed the broadcaster's editorial guidelines on accuracy.
A representative for the broadcaster said: "The regulator's decision is in accordance with the conclusions of the corporation's inquiry, that there was a serious error in the film 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 comply with the authority's determination in complete. We will follow the directive as soon as the schedule and language are determined."
