The BBC committed a "major breach" of media regulations by omitting to mention that the narrator of a documentary about the Gaza situation was the child of a Hamas administrator, as ruled by UK media regulator Ofcom.
An inquiry by Ofcom into the programme Gaza: How to Survive a Warzone has found that the film was "materially misleading".
The BBC's director general had already issued an apology, saying there had been "a significant failing in relation to factual correctness".
Ofcom has directed the corporation to transmit a peak-time declaration about its decisions.
"Given this constitutes a major infringement of our rules, we are directing the BBC to transmit a announcement of our findings against it on BBC Two at 9pm, with a timing to be confirmed," the statement read.
'Potential to Damage Trust'
The watchdog's statement said: "The inquiry we conducted determined that the film's omission to reveal that the presenter's father served in a role in the Hamas-administered government was significantly deceptive.
"It meant that the viewers did not have essential details which may have been extremely pertinent to their judgment of the presenter and the details he presented.
"Trust is at the core of the bond between a broadcaster and its public, notably for a public service broadcaster such as the British Broadcasting Corporation.
"This error had the possibility to damage the very considerable amounts of trust that viewers would have invested in a BBC factual programme about the conflict in Gaza."
The documentary was withdrawn from iPlayer in last February after the boy's familial connections came to light, and in July an internal BBC review found it violated the corporation's content policies on accuracy.
A representative for the broadcaster said: "The regulator's decision is in accordance with the results 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 clause 2.2 of Ofcom's Broadcasting Code.
"We expressed regret for this and we agree with the authority's determination in full. We will follow the sanction as soon as the date and wording are finalised."
