The BBC engaged in a "major breach" of industry standards by omitting to mention that the presenter of a programme about Gaza was the son of a Hamas official, according to regulatory body Ofcom.
An investigation by the broadcasting watchdog into Gaza: How to Survive a Warzone has found that the documentary was "substantially inaccurate".
The chief executive of the broadcaster had already issued an apology, stating there had been "a serious error in relation to accuracy".
The authority has ordered the broadcaster to air a evening declaration about its conclusions.
"Since this amounts to a major infringement of our code, we are instructing the corporation to transmit a message of our findings against it on BBC Two at 9pm, with a date to be finalised," the statement read.
'Potential to Damage Credibility'
The authority's announcement stated: "Our investigation found that the documentary's omission to reveal that the voice's parent held a position in the Hamas-controlled administration was substantially inaccurate.
"Consequently that the viewers did not have critical information which may have been very significant to their judgment of the voice and the details he provided.
"Trust is at the core of the relationship between a broadcaster and its viewers, particularly for a national broadcasting corporation such as the British Broadcasting Corporation.
"This failing had the possibility to erode the significantly high degrees of confidence that the public would have invested in a documentary produced by the BBC about the Israel-Gaza war."
The programme was pulled from iPlayer in the month of February after the boy's familial connections came to light, and in July an corporation's own inquiry concluded it infringed the organization's editorial guidelines on accuracy.
A representative for the broadcaster commented: "The Ofcom ruling is in accordance with the findings of Peter Johnston's review, that there was a serious error in the film in relation to the BBC's Editorial Guidelines on accuracy, which aligns with clause 2.2 of Ofcom's Broadcasting Code.
"We issued an apology for this and we comply with the regulator's ruling in its entirety. We will adhere to the penalty as soon as the timing and language are finalised."
