The BBC was found to have committed a "significant breach" of industry standards by omitting to mention that the narrator of a programme about Gaza was the son of a Hamas official, as determined by British broadcasting authority Ofcom.
An inquiry by the media regulator into Gaza: How to Survive a Warzone has concluded that the programme was "substantially inaccurate".
The chief executive of the broadcaster had earlier expressed regret, saying there had been "a serious error in relation to accuracy".
The regulator has instructed the broadcaster to air a peak-time declaration about its findings.
"As this represents a major infringement of our regulations, we are instructing the corporation to air a message of our findings against it on BBC2 at nine o'clock in the evening, with a schedule to be determined," it said.
'Possibility to Undermine Trust'
The regulator's report stated: "Our probe determined that the documentary's lack of disclosure that the presenter's father served in a post in the Hamas-run authority was substantially inaccurate.
"This implied that the audience did not have critical information which may have been highly relevant to their evaluation of the voice and the details he provided.
"Confidence is at the center of the bond between a television network and its viewers, particularly for a state-funded media outlet such as the public broadcaster.
"This oversight had the possibility to erode the very considerable amounts of credibility that viewers would have invested in a documentary produced by the BBC about the Gaza conflict."
The programme was withdrawn from iPlayer in the month of February after the narrator's personal associations came to light, and in the month of July an internal BBC review determined it infringed the broadcaster's editorial guidelines on truthfulness.
A representative for the broadcaster commented: "The regulator's decision is in line with the results of the internal assessment, that there was a significant failing in the programme in relation to the corporation's content standards on accuracy, which aligns with Rule 2.2 of Ofcom's Broadcasting Code.
"We expressed regret for this and we accept the authority's determination in complete. We will comply with the penalty as soon as the date and wording are finalised."
