The BBC committed a "serious breach" of media regulations by failing to disclose that the presenter of a programme about Gaza was the child of a Hamas administrator, as determined by British broadcasting authority Ofcom.
An probe by the media regulator into Gaza: How to Survive a Warzone has concluded that the film was "significantly deceptive".
The BBC's director general had earlier expressed regret, stating there had been "a serious error in relation to factual correctness".
The regulator has instructed the corporation to broadcast a peak-time declaration about its findings.
"Since this amounts to a major infringement of our rules, we are instructing the broadcaster to transmit a statement of our conclusions against it on BBC2 at nine o'clock in the evening, with a schedule to be finalised," it said.
'Possibility to Erode Credibility'
The watchdog's announcement declared: "Our investigation determined that the film's lack of disclosure that the presenter's father served in a position in the Hamas-run authority was substantially inaccurate.
"This implied that the audience did not have vital facts which may have been very significant to their judgment of the voice and the content he provided.
"Credibility is at the center of the bond between a television network and its viewers, notably for a public service broadcaster such as the British Broadcasting Corporation.
"This failing had the potential to undermine the exceptionally strong levels of credibility that viewers would have invested in a factual film from the broadcaster about the Israel-Gaza war."
The programme was removed from the BBC's streaming service in February after the presenter's family links came to light, and in this past July an broadcaster's internal assessment determined it violated the corporation's content policies on truthfulness.
A corporation official said: "The Ofcom ruling is in agreement with the findings of Peter Johnston's review, that there was a major oversight in the film in relation to the corporation's content standards on factual correctness, which reflects regulation 2.2 of the authority's broadcasting regulations.
"We expressed regret for this and we comply with Ofcom's decision in its entirety. We will follow the directive as soon as the date and language are confirmed."
