The BBC was found to have committed a "major breach" of industry standards by omitting to mention that the voice of a film about the Gaza situation was the son of a Hamas administrator, as determined by regulatory body Ofcom.
An inquiry by Ofcom into Gaza: How to Survive a Warzone has determined that the programme was "significantly deceptive".
The BBC's director general had earlier expressed regret, noting there had been "a major oversight in relation to truthfulness".
The regulator has ordered the BBC to air a prime-time declaration about its findings.
"Since this amounts to a serious breach of our code, we are instructing the BBC to transmit a announcement of our determinations against it on BBC Two at nine o'clock in the evening, with a timing to be confirmed," the regulator stated.
'Risk to Damage Credibility'
The watchdog's report said: "Our investigation determined that the programme's omission to reveal that the voice's male guardian held a position in the Hamas-run authority was substantially inaccurate.
"It meant that the audience did not have essential details which may have been highly relevant to their assessment of the narrator and the content he presented.
"Confidence is at the core of the bond between a television network and its viewers, particularly for a public service broadcaster such as the British Broadcasting Corporation.
"This error had the potential to damage the significantly high levels of trust that viewers would have put in a documentary produced by the BBC about the conflict in Gaza."
The film was pulled from the BBC's streaming service in February after the narrator's familial connections emerged, and in July an broadcaster's internal assessment determined it infringed the organization's editorial guidelines on accuracy.
A representative for the broadcaster commented: "The regulator's decision is in agreement with the conclusions of Peter Johnston's review, that there was a significant failing in the programme in relation to the corporation's content standards on accuracy, which reflects clause 2.2 of Ofcom's Broadcasting Code.
"We have apologised for this and we accept the authority's determination in its entirety. We will follow the penalty as soon as the timing and language are finalised."
