The BBC committed a "major breach" of broadcasting rules by failing to disclose that the narrator of a film about the Gaza situation was the son of a Hamas administrator, as ruled by regulatory body Ofcom.
An investigation by the broadcasting watchdog into Gaza: How to Survive a Warzone has determined that the film was "materially misleading".
The chief executive of the broadcaster had already issued an apology, saying there had been "a significant failing in relation to truthfulness".
The authority has directed the BBC to broadcast a prime-time declaration about its conclusions.
"Given this constitutes a serious breach of our rules, we are ordering the broadcaster to air a message of our conclusions against it on BBC2 at nine o'clock in the evening, with a date to be determined," it said.
'Risk to Erode Credibility'
The watchdog's announcement stated: "Our investigation found that the film's omission to reveal that the presenter's father occupied a role in the Hamas-run administration was significantly deceptive.
"It meant that the viewers did not have critical information which may have been very significant to their judgment of the presenter and the content he shared.
"Trust is at the heart of the relationship between a broadcaster and its viewers, particularly for a state-funded media outlet such as the BBC.
"This error had the possibility to undermine the significantly high amounts of confidence that viewers would have put in a BBC factual programme about the conflict in Gaza."
The film was withdrawn from the online platform in February after the narrator's familial connections were revealed, and in the month of July an internal BBC review concluded it breached the broadcaster's editorial guidelines on truthfulness.
A corporation official commented: "The regulator's decision is in agreement with the findings of the internal assessment, that there was a significant failing in the documentary in relation to the BBC's Editorial Guidelines on accuracy, which aligns with clause 2.2 of Ofcom's Broadcasting Code.
"We have apologised for this and we agree with Ofcom's decision in complete. We will follow the penalty as soon as the timing and wording are determined."
