The BBC committed a "major breach" of industry standards by omitting to mention that the voice of a programme about the Gaza conflict was the son of a Hamas representative, as ruled by UK media regulator Ofcom.
An probe by the media regulator into the documentary titled Gaza: How to Survive a Warzone has determined that the programme was "materially misleading".
The head of the BBC had earlier expressed regret, saying there had been "a serious error in relation to truthfulness".
The regulator has instructed the corporation to transmit a peak-time declaration about its decisions.
"As this represents a significant violation of our regulations, we are ordering the corporation to transmit a message of our conclusions against it on BBC2 at nine o'clock in the evening, with a schedule to be determined," it said.
'Risk to Erode Trust'
The watchdog's statement declared: "The inquiry we conducted found that the film's failure to disclose that the presenter's parent occupied a position in the Hamas-run administration was substantially inaccurate.
"Consequently that the public did not have vital facts which may have been very significant to their assessment of the narrator and the content he shared.
"Trust is at the center of the connection between a television network and its audience, especially for a public service broadcaster such as the public broadcaster.
"This error had the risk to undermine the significantly high degrees of trust that audiences would have invested in a factual film from the broadcaster about the conflict in Gaza."
The documentary was withdrawn from the BBC's streaming service in last February after the boy's family links emerged, and in July an internal BBC review determined it infringed the broadcaster's editorial guidelines on accuracy.
A corporation official stated: "The regulator's decision is in agreement with the results of Peter Johnston's review, that there was a major oversight in the film in relation to the corporation's content standards on accuracy, which reflects regulation 2.2 of the authority's broadcasting regulations.
"We have apologised for this and we comply with Ofcom's decision in full. We will adhere to the sanction as soon as the date and wording are finalised."
