The BBC was found to have committed a "serious breach" of industry standards by omitting to mention that the presenter of a programme about Gaza was the offspring of a Hamas official, as determined by regulatory body Ofcom.
An investigation by Ofcom into the programme Gaza: How to Survive a Warzone has found that the documentary 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 BBC to air a peak-time announcement about its conclusions.
"Given this constitutes a major infringement of our rules, we are directing the broadcaster to air a statement of our conclusions against it on the BBC's second channel at nine o'clock in the evening, with a schedule to be determined," the regulator stated.
'Potential to Erode Confidence'
The regulator's statement declared: "Our probe determined that the programme's omission to reveal that the narrator's father served in a post in the Hamas-administered government was substantially inaccurate.
"Consequently that the public did not have critical information which may have been very significant to their evaluation of the presenter and the information he provided.
"Credibility is at the center of the connection between a television network and its viewers, especially for a public service broadcaster such as the British Broadcasting Corporation.
"This failing had the possibility to undermine the exceptionally strong degrees of credibility that viewers would have put in a BBC factual programme about the conflict in Gaza."
The documentary was removed from iPlayer in last February after the presenter's familial connections were revealed, and in July an corporation's own inquiry concluded it infringed the broadcaster's editorial guidelines on truthfulness.
A BBC spokesperson stated: "The Ofcom ruling is in line with the results of Peter Johnston's review, that there was a significant failing in the film in relation to the broadcaster's journalistic policies on truthfulness, which reflects Rule 2.2 of the authority's broadcasting regulations.
"We have apologised for this and we accept Ofcom's decision in full. We will follow the penalty as soon as the date and wording are confirmed."
