The BBC engaged in a "serious breach" of industry standards by not revealing that the voice of a documentary about the Gaza situation was the offspring of a Hamas representative, as determined by regulatory body Ofcom.
An inquiry by the media regulator into Gaza: How to Survive a Warzone has concluded that the programme was "substantially inaccurate".
The BBC's director general had earlier expressed regret, stating there had been "a serious error in relation to factual correctness".
The authority has ordered the broadcaster to transmit a peak-time declaration about its decisions.
"Given this constitutes a major infringement of our rules, we are ordering the corporation to transmit a statement of our findings against it on BBC Two at 9pm, with a schedule to be determined," it said.
'Possibility to Undermine Confidence'
The regulator's statement said: "Our probe concluded that the film's failure to disclose that the voice's parent served in a role in the Hamas-administered administration was materially misleading.
"Consequently that the audience did not have vital facts which may have been extremely pertinent to their assessment of the voice and the information he shared.
"Confidence is at the center of the relationship between a media organization and its viewers, notably for a public service broadcaster such as the BBC.
"This error had the possibility to undermine the significantly high amounts of trust that viewers would have placed in a documentary produced by the BBC about the conflict in Gaza."
The programme was withdrawn from iPlayer in last February after the boy's family links emerged, and in the month of July an corporation's own inquiry determined it violated the organization's editorial guidelines on truthfulness.
A corporation official said: "The Ofcom ruling is in agreement with the conclusions of the internal assessment, that there was a significant failing in the programme in relation to the corporation's content standards on truthfulness, which corresponds to Rule 2.2 of the regulator's media standards.
"We expressed regret for this and we comply with the regulator's ruling in complete. We will comply with the penalty as soon as the timing and wording are finalised."
