The British broadcaster was found to have committed a "major breach" of media regulations by not revealing that the voice of a programme about Gaza was the offspring of a Hamas administrator, as determined by regulatory body Ofcom.
An inquiry by Ofcom into Gaza: How to Survive a Warzone has found that the documentary was "substantially inaccurate".
The BBC's director general had earlier expressed regret, saying there had been "a significant failing in relation to accuracy".
Ofcom has instructed the broadcaster to air a evening announcement about its conclusions.
"Since this amounts to a major infringement of our rules, we are instructing the BBC to transmit a statement of our findings against it on BBC Two at nine o'clock in the evening, with a date to be confirmed," the regulator stated.
'Risk to Erode Trust'
The regulator's report stated: "Our investigation determined that the documentary's failure to disclose that the narrator's father held a position in the Hamas-run government was substantially inaccurate.
"This implied that the audience did not have critical information which may have been extremely pertinent to their assessment of the narrator and the content he presented.
"Trust is at the heart of the relationship between a television network and its public, particularly for a national broadcasting corporation such as the British Broadcasting Corporation.
"This error had the potential to undermine the significantly high levels of trust that the public would have invested in a documentary produced by the BBC about the conflict in Gaza."
The documentary was withdrawn from the online platform in February after the narrator's personal associations were revealed, and in this past July an broadcaster's internal assessment determined it infringed the broadcaster's journalistic standards on factual correctness.
A corporation official commented: "The authority's determination is in line with the conclusions of the internal assessment, that there was a serious error in the programme in relation to the broadcaster's journalistic policies on truthfulness, which aligns with Rule 2.2 of the regulator's media standards.
"We expressed regret for this and we accept the authority's determination in full. We will comply with the penalty as soon as the timing and wording are determined."
