The BBC engaged in a "serious breach" of industry standards by omitting to mention that the narrator of a programme about the Gaza conflict was the offspring of a Hamas official, as ruled by British broadcasting authority Ofcom.
An inquiry by the broadcasting watchdog into the documentary titled Gaza: How to Survive a Warzone has found that the programme was "significantly deceptive".
The BBC's director general had previously apologised, stating there had been "a serious error in relation to factual correctness".
The regulator has ordered the BBC to transmit a peak-time declaration about its findings.
"As this represents a major infringement of our code, we are instructing the broadcaster to transmit a announcement of our determinations against it on BBC2 at nine o'clock in the evening, with a schedule to be determined," it said.
The watchdog's report said: "Our investigation determined that the film's lack of disclosure that the voice's male guardian held a position in the Hamas-administered government was significantly deceptive.
"This implied that the public did not have vital facts which may have been highly relevant to their assessment of the voice and the information he shared.
"Trust is at the core of the connection between a broadcaster and its viewers, particularly for a state-funded media outlet such as the BBC.
"This failing had the risk to undermine the exceptionally strong degrees of trust that the public would have placed in a factual film from the broadcaster about the conflict in Gaza."
The documentary was pulled from iPlayer in last February after the boy's familial connections emerged, and in the month of July an corporation's own inquiry found it breached the corporation's editorial guidelines on truthfulness.
A corporation official said: "The Ofcom ruling is in agreement with the findings of Peter Johnston's review, that there was a significant failing in the programme in relation to the BBC's Editorial Guidelines on truthfulness, which reflects clause 2.2 of Ofcom's Broadcasting Code.
"We expressed regret for this and we agree with the regulator's ruling in full. We will follow the sanction as soon as the date and wording are finalised."
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