The BBC was found to have committed a "significant breach" of media regulations by not revealing that the narrator of a film about the Gaza situation was the child of a Hamas representative, as ruled by British broadcasting authority Ofcom.
An inquiry by the media regulator into Gaza: How to Survive a Warzone has found that the documentary was "materially misleading".
The BBC's director general had already issued an apology, stating there had been "a serious error in relation to truthfulness".
The regulator has ordered the corporation to broadcast a peak-time declaration about its conclusions.
"Since this amounts to a major infringement of our code, we are instructing the corporation to broadcast a message of our findings against it on BBC2 at 9pm, with a schedule to be determined," the regulator stated.
'Possibility to Undermine Trust'
The watchdog's statement declared: "Our investigation determined that the programme's lack of disclosure that the presenter's parent held a post in the Hamas-run administration was substantially inaccurate.
"It meant that the viewers did not have vital facts which may have been extremely pertinent to their assessment of the voice and the content he shared.
"Trust is at the core of the bond between a media organization and its viewers, especially for a national broadcasting corporation such as the British Broadcasting Corporation.
"This oversight had the potential to damage the very considerable degrees of credibility that the public would have put in a documentary produced by the BBC about the conflict in Gaza."
The documentary was removed from the BBC's streaming service in February after the presenter's familial connections came to light, and in July an corporation's own inquiry concluded it violated the broadcaster's journalistic standards on factual correctness.
A corporation official stated: "The regulator's decision is in accordance with the results of the corporation's inquiry, that there was a major oversight in the film in relation to the corporation's content standards on accuracy, which aligns with Rule 2.2 of the regulator's media standards.
"We have apologised for this and we comply with the authority's determination in full. We will adhere to the sanction as soon as the date and language are confirmed."
