The BBC committed a "serious breach" of media regulations by failing to disclose that the narrator of a programme about Gaza was the offspring of a Hamas official, as determined by British broadcasting authority Ofcom.
An inquiry by Ofcom into the documentary titled Gaza: How to Survive a Warzone has found that the documentary was "substantially inaccurate".
The BBC's director general had earlier expressed regret, stating there had been "a significant failing in relation to truthfulness".
The authority has instructed the broadcaster to transmit a evening declaration about its decisions.
"Since this amounts to a serious breach of our rules, we are directing the broadcaster to transmit a announcement of our findings against it on BBC Two at nine o'clock in the evening, with a date to be finalised," the statement read.
'Potential to Damage Trust'
The watchdog's statement stated: "Our probe concluded that the film's failure to disclose that the narrator's male guardian held a post in the Hamas-controlled authority was materially misleading.
"Consequently that the audience did not have critical information which may have been very significant to their judgment of the narrator and the content he provided.
"Credibility is at the core of the relationship between a media organization and its public, particularly for a public service broadcaster such as the BBC.
"This failing had the possibility to damage the exceptionally strong levels of trust that viewers would have placed in a BBC factual programme about the conflict in Gaza."
The film was withdrawn from the BBC's streaming service in February after the boy's familial connections came to light, and in the month of July an corporation's own inquiry concluded it violated the broadcaster's journalistic standards on factual correctness.
A corporation official said: "The regulator's decision is in agreement with the conclusions of Peter Johnston's review, that there was a major oversight in the film in relation to the BBC's Editorial Guidelines on factual correctness, which reflects clause 2.2 of the regulator's media standards.
"We issued an apology for this and we accept Ofcom's decision in complete. We will comply with the sanction as soon as the schedule and wording are finalised."
