The BBC was found to have committed a "major breach" of media regulations by omitting to mention that the presenter of a programme about Gaza was the offspring of a Hamas representative, as ruled by UK media regulator Ofcom.
An inquiry by Ofcom into the programme Gaza: How to Survive a Warzone has determined that the film was "substantially inaccurate".
The chief executive of the broadcaster had earlier expressed regret, saying there had been "a significant failing in relation to truthfulness".
The regulator has instructed the broadcaster to transmit a peak-time declaration about its findings.
"Given this constitutes a major infringement of our rules, we are instructing the corporation to transmit a statement of our findings against it on BBC2 at nine o'clock in the evening, with a schedule to be confirmed," the statement read.
'Possibility to Undermine Trust'
The regulator's report stated: "The inquiry we conducted concluded that the film's omission to reveal that the presenter's male guardian occupied a post in the Hamas-controlled administration was substantially inaccurate.
"It meant that the public did not have critical information which may have been highly relevant to their assessment of the voice and the information he shared.
"Credibility is at the heart of the connection between a broadcaster and its audience, particularly for a national broadcasting corporation such as the BBC.
"This oversight had the potential to damage the very considerable degrees of credibility that audiences would have put in a factual film from the broadcaster about the conflict in Gaza."
The documentary was pulled from the online platform in last February after the presenter's family links were revealed, and in July an broadcaster's internal assessment concluded it infringed the organization's editorial guidelines on accuracy.
A corporation official said: "The regulator's decision is in agreement with the conclusions of Peter Johnston's review, that there was a serious error 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 have apologised for this and we agree with the regulator's ruling in complete. We will adhere to the penalty as soon as the schedule and wording are determined."