The BBC was found to have committed a "major breach" of media regulations by not revealing that the narrator of a film about the Gaza situation was the offspring of a Hamas administrator, as ruled by regulatory body Ofcom.
An probe by the broadcasting watchdog into the programme Gaza: How to Survive a Warzone has found that the programme was "materially misleading".
The BBC's director general had already issued an apology, saying there had been "a serious error in relation to accuracy".
Ofcom has ordered the BBC to transmit a prime-time declaration about its decisions.
"Given this constitutes a major infringement of our regulations, we are directing the broadcaster to broadcast a statement of our findings against it on BBC2 at nine o'clock in the evening, with a timing to be finalised," the statement read.
'Potential to Erode Trust'
The watchdog's report said: "The inquiry we conducted determined that the programme's lack of disclosure that the voice's male guardian held a position in the Hamas-run government was significantly deceptive.
"Consequently that the audience did not have critical information which may have been very significant to their evaluation of the presenter and the content he shared.
"Confidence is at the core of the bond between a broadcaster and its audience, notably for a state-funded media outlet such as the public broadcaster.
"This oversight had the potential to undermine the very considerable levels of credibility that the public would have invested in a documentary produced by the BBC about the conflict in Gaza."
The film was pulled from the online platform in February after the presenter's personal associations emerged, and in this past July an broadcaster's internal assessment determined it violated the organization's editorial guidelines on accuracy.
A corporation official said: "The authority's determination is in line with the results of Peter Johnston's review, that there was a serious error in the documentary in relation to the BBC's Editorial Guidelines on accuracy, which reflects clause 2.2 of Ofcom's Broadcasting Code.
"We expressed regret for this and we accept the authority's determination in full. We will adhere to the sanction as soon as the schedule and wording are confirmed."
