The BBC was found to have committed a "major breach" of media regulations by not revealing that the voice of a programme about the Gaza conflict was the son of a Hamas official, according to British broadcasting authority Ofcom.
An inquiry by the media regulator into Gaza: How to Survive a Warzone has determined that the film was "significantly deceptive".
The BBC's director general had earlier expressed regret, stating there had been "a significant failing in relation to truthfulness".
Ofcom has ordered the BBC to transmit a peak-time declaration about its findings.
"Since this amounts to a major infringement of our regulations, we are instructing the broadcaster to broadcast a announcement of our determinations against it on BBC2 at 21:00, with a schedule to be confirmed," the statement read.
'Potential to Damage Trust'
The regulator's statement declared: "The inquiry we conducted found that the documentary's lack of disclosure that the voice's father held a position in the Hamas-run administration was materially misleading.
"This implied that the audience did not have essential details which may have been extremely pertinent to their assessment of the voice and the information he provided.
"Credibility is at the core of the bond between a media organization and its viewers, especially for a national broadcasting corporation such as the public broadcaster.
"This failing had the potential to undermine the very considerable levels of confidence that the public would have placed in a documentary produced by the BBC about the Israel-Gaza war."
The programme was pulled from the BBC's streaming service in the month of February after the boy's family links came to light, and in this past July an corporation's own inquiry found it infringed the broadcaster's journalistic standards on truthfulness.
A corporation official said: "The authority's determination is in agreement with the findings of the internal assessment, that there was a significant failing in the film in relation to the corporation's content standards on truthfulness, which reflects regulation 2.2 of Ofcom's Broadcasting Code.
"We have apologised for this and we agree with Ofcom's decision in its entirety. We will comply with the penalty as soon as the schedule and wording are confirmed."
