The BBC committed a "significant breach" of broadcasting rules by omitting to mention that the voice of a programme about the Gaza conflict was the child of a Hamas administrator, as determined by regulatory body Ofcom.
An probe by Ofcom into Gaza: How to Survive a Warzone has concluded that the programme was "significantly deceptive".
The head of the BBC had earlier expressed regret, noting there had been "a significant failing in relation to accuracy".
The regulator has directed the corporation to transmit a prime-time declaration about its findings.
"Given this constitutes a major infringement of our rules, we are ordering the corporation to air a statement of our conclusions against it on BBC2 at 21:00, with a schedule to be determined," it said.
'Potential to Erode Credibility'
The watchdog's announcement declared: "Our probe determined that the documentary's failure to disclose that the narrator's father served in a role in the Hamas-controlled authority was significantly deceptive.
"Consequently that the public did not have essential details which may have been very significant to their evaluation of the presenter and the details he provided.
"Credibility is at the heart of the bond between a television network and its public, notably for a public service broadcaster such as the public broadcaster.
"This failing had the potential to undermine the very considerable degrees of credibility that the public would have invested in a documentary produced by the BBC about the Gaza conflict."
The film was withdrawn from the BBC's streaming service in the month of February after the boy's personal associations came to light, and in this past July an internal BBC review found it infringed the broadcaster's content policies on truthfulness.
A representative for the broadcaster said: "The Ofcom ruling is in agreement with the findings of Peter Johnston's review, that there was a serious error in the programme in relation to the corporation's content standards on factual correctness, which reflects clause 2.2 of the regulator's media standards.
"We expressed regret for this and we agree with the regulator's ruling in its entirety. We will follow the sanction as soon as the date and language are determined."
