The BBC committed a "major breach" of broadcasting rules by omitting to mention that the voice of a film about the Gaza situation was the son of a Hamas representative, as ruled by British broadcasting authority Ofcom.
An investigation by the media regulator into Gaza: How to Survive a Warzone has found that the programme was "significantly deceptive".
The chief executive of the broadcaster had earlier expressed regret, noting there had been "a serious error in relation to truthfulness".
The authority has instructed the broadcaster to air a peak-time statement about its findings.
"As this represents a major infringement of our rules, we are directing the broadcaster to transmit a statement of our conclusions against it on the BBC's second channel at 21:00, with a timing to be confirmed," the statement read.
'Potential to Erode Credibility'
The watchdog's statement said: "Our probe determined that the programme's lack of disclosure that the voice's father served in a role in the Hamas-run authority was significantly deceptive.
"This implied that the public did not have vital facts which may have been extremely pertinent to their evaluation of the narrator and the content he shared.
"Trust is at the center of the relationship between a television network and its audience, particularly for a public service broadcaster such as the public broadcaster.
"This error had the possibility to damage the exceptionally strong degrees of confidence that the public would have placed in a documentary produced by the BBC about the conflict in Gaza."
The programme was removed from the online platform in February after the boy's familial connections came to light, and in this past July an broadcaster's internal assessment found it breached the broadcaster's content policies on truthfulness.
A representative for the broadcaster stated: "The Ofcom ruling is in line with the findings of Peter Johnston's review, that there was a major oversight in the documentary in relation to the corporation's content standards on accuracy, which aligns with clause 2.2 of Ofcom's Broadcasting Code.
"We have apologised for this and we comply with the regulator's ruling in full. We will comply with the penalty as soon as the schedule and wording are determined."
