The BBC engaged in a "major breach" of media regulations by not revealing that the voice of a programme about Gaza was the child of a Hamas administrator, as ruled by British broadcasting authority Ofcom.
An investigation by the broadcasting watchdog into Gaza: How to Survive a Warzone has concluded that the documentary was "materially misleading".
The chief executive of the broadcaster had earlier expressed regret, saying there had been "a serious error in relation to factual correctness".
The authority has ordered the broadcaster to air a peak-time statement about its findings.
"Since this amounts to a significant violation of our rules, we are directing the broadcaster to air a statement of our conclusions against it on the BBC's second channel at 9pm, with a schedule to be determined," it said.
'Possibility to Erode Trust'
The authority's statement stated: "The inquiry we conducted determined that the documentary's failure to disclose that the narrator's male guardian held a post in the Hamas-controlled administration was materially misleading.
"This implied that the viewers did not have vital facts which may have been very significant to their evaluation of the presenter and the content he presented.
"Credibility is at the center of the bond between a television network and its public, especially for a public service broadcaster such as the BBC.
"This oversight had the risk to damage the very considerable degrees of credibility that the public would have placed in a factual film from the broadcaster about the Israel-Gaza war."
The film was withdrawn from iPlayer in February after the boy's familial connections were revealed, and in this past July an internal BBC review concluded it breached the organization's content policies on factual correctness.
A representative for the broadcaster said: "The authority's determination is in agreement with the conclusions of Peter Johnston's review, that there was a major oversight in the documentary in relation to the BBC's Editorial Guidelines on accuracy, which corresponds to regulation 2.2 of the authority's broadcasting regulations.
"We expressed regret for this and we agree with Ofcom's decision in its entirety. We will follow the penalty as soon as the schedule and wording are confirmed."
