The British broadcaster committed a "serious breach" of media regulations by omitting to mention that the voice of a film about Gaza was the son of a Hamas representative, as determined by British broadcasting authority Ofcom.
An inquiry by the media regulator into Gaza: How to Survive a Warzone has concluded that the documentary was "substantially inaccurate".
The BBC's director general had previously apologised, stating there had been "a major oversight in relation to accuracy".
The authority has directed the BBC to transmit a prime-time declaration about its conclusions.
"Since this amounts to a serious breach of our code, we are ordering the BBC to broadcast a statement of our conclusions against it on the BBC's second channel at nine o'clock in the evening, with a date to be determined," the regulator stated.
'Risk to Erode Confidence'
The regulator's announcement stated: "The inquiry we conducted determined that the programme's lack of disclosure that the presenter's male guardian held a post in the Hamas-controlled authority was substantially inaccurate.
"Consequently that the viewers did not have vital facts which may have been highly relevant to their assessment of the voice and the content he presented.
"Credibility is at the center of the relationship between a media organization and its audience, notably for a national broadcasting corporation such as the British Broadcasting Corporation.
"This oversight had the potential to erode the exceptionally strong degrees of confidence that viewers would have put in a BBC factual programme about the Gaza conflict."
The programme was removed from the BBC's streaming service in February after the presenter's familial connections were revealed, and in this past July an corporation's own inquiry concluded it breached the corporation's editorial guidelines on factual correctness.
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 serious error in the programme in relation to the broadcaster's journalistic policies on accuracy, which aligns with Rule 2.2 of the regulator's media standards.
"We have apologised for this and we agree with Ofcom's decision in its entirety. We will comply with the penalty as soon as the timing and language are determined."
