The BBC was found to have committed a "major breach" of broadcasting rules by omitting to mention that the presenter of a programme about Gaza was the offspring of a Hamas representative, according to regulatory body Ofcom.
An investigation by the media regulator into Gaza: How to Survive a Warzone has concluded that the film was "substantially inaccurate".
The head of the BBC had previously apologised, stating there had been "a serious error in relation to accuracy".
Ofcom has ordered the corporation to broadcast a evening declaration about its findings.
"Since this amounts to a significant violation of our code, we are ordering the corporation to broadcast a announcement of our findings against it on BBC Two at nine o'clock in the evening, with a schedule to be finalised," the statement read.
'Risk to Erode Credibility'
The authority's statement declared: "Our investigation found that the film's omission to reveal that the voice's father served in a position in the Hamas-administered authority was substantially inaccurate.
"This implied that the public did not have vital facts which may have been very significant to their assessment of the narrator and the details he provided.
"Credibility is at the heart of the bond between a broadcaster and its audience, especially for a state-funded media outlet such as the BBC.
"This failing had the possibility to damage the very considerable degrees of trust that audiences would have placed in a factual film from the broadcaster about the conflict in Gaza."
The programme was removed from the online platform in last February after the presenter's familial connections came to light, and in the month of July an internal BBC review concluded it infringed the corporation's editorial guidelines on accuracy.
A representative for the broadcaster stated: "The regulator's decision is in accordance with the findings of Peter Johnston's review, that there was a serious error in the documentary in relation to the broadcaster's journalistic policies on factual correctness, which corresponds to clause 2.2 of the authority's broadcasting regulations.
"We have apologised for this and we accept Ofcom's decision in complete. We will comply with the penalty as soon as the schedule and wording are finalised."
