The BBC engaged in a "significant breach" of media regulations by not revealing that the voice of a film about the Gaza situation was the son of a Hamas official, as determined by regulatory body Ofcom.
An investigation by Ofcom into the documentary titled Gaza: How to Survive a Warzone has concluded that the programme was "significantly deceptive".
The chief executive of the broadcaster had already issued an apology, noting there had been "a major oversight in relation to accuracy".
The authority has instructed the broadcaster to transmit a peak-time announcement about its findings.
"As this represents a significant violation of our code, we are ordering the broadcaster to air a message of our findings against it on BBC2 at 9pm, with a date to be confirmed," it said.
'Possibility to Undermine Confidence'
The authority's statement said: "Our probe concluded that the documentary's omission to reveal that the voice's male guardian held a role in the Hamas-run government was significantly deceptive.
"This implied that the audience did not have vital facts which may have been extremely pertinent to their evaluation of the voice and the content he provided.
"Trust is at the core of the bond between a media organization and its viewers, notably for a public service broadcaster such as the British Broadcasting Corporation.
"This failing had the possibility to damage the very considerable degrees of trust that audiences would have placed in a documentary produced by the BBC about the Israel-Gaza war."
The film was pulled from the BBC's streaming service in the month of February after the narrator's family links were revealed, and in the month of July an corporation's own inquiry found it violated the corporation's editorial guidelines on factual correctness.
A representative for the broadcaster said: "The Ofcom ruling is in agreement with the results of the corporation's inquiry, that there was a significant failing in the documentary in relation to the corporation's content standards on accuracy, which reflects clause 2.2 of the authority's broadcasting regulations.
"We have apologised for this and we comply with Ofcom's decision in its entirety. We will comply with the penalty as soon as the timing and wording are determined."
