The BBC engaged in a "significant breach" of broadcasting rules by not revealing that the presenter of a documentary about the Gaza situation was the child of a Hamas representative, according to regulatory body Ofcom.
An investigation by Ofcom into Gaza: How to Survive a Warzone has determined that the film was "substantially inaccurate".
The chief executive of the broadcaster had previously apologised, saying there had been "a serious error in relation to factual correctness".
The regulator has directed the broadcaster to air a evening declaration about its conclusions.
"Given this constitutes a major infringement of our regulations, we are instructing the corporation to air a statement of our findings against it on BBC Two at 21:00, with a schedule to be confirmed," the regulator stated.
'Risk to Damage Trust'
The watchdog's announcement stated: "The inquiry we conducted found that the programme's omission to reveal that the narrator's father served in a role in the Hamas-controlled administration was significantly deceptive.
"It meant that the viewers did not have vital facts which may have been highly relevant to their assessment of the narrator and the content he presented.
"Confidence is at the center of the relationship between a television network and its public, particularly for a national broadcasting corporation such as the BBC.
"This failing had the potential to damage the very considerable amounts of trust that audiences would have invested in a BBC factual programme about the Gaza conflict."
The film was removed from the BBC's streaming service in last February after the presenter's familial connections came to light, and in July an corporation's own inquiry determined it breached the corporation's editorial guidelines on truthfulness.
A BBC spokesperson said: "The Ofcom ruling is in agreement with the findings of the internal assessment, that there was a significant failing in the film in relation to the broadcaster's journalistic policies on accuracy, which reflects clause 2.2 of Ofcom's Broadcasting Code.
"We issued an apology for this and we accept the regulator's ruling in full. We will comply with the penalty as soon as the schedule and wording are confirmed."
