The BBC engaged in a "major breach" of media regulations by omitting to mention that the voice of a film about the Gaza situation was the son of a Hamas official, as ruled by regulatory body Ofcom.
An investigation by Ofcom into the documentary titled Gaza: How to Survive a Warzone has found that the programme was "substantially inaccurate".
The BBC's director general had already issued an apology, noting there had been "a significant failing in relation to accuracy".
The authority has instructed the broadcaster to air a prime-time declaration about its decisions.
"Given this constitutes a serious breach of our code, we are instructing the BBC to transmit a announcement of our determinations against it on BBC Two at nine o'clock in the evening, with a schedule to be determined," it said.
'Risk to Erode Confidence'
The watchdog's report stated: "The inquiry we conducted found that the film's omission to reveal that the presenter's father served in a position in the Hamas-run government was materially misleading.
"Consequently that the public did not have vital facts which may have been very significant to their evaluation of the voice and the content he shared.
"Trust is at the center of the bond between a broadcaster and its viewers, particularly for a national broadcasting corporation such as the BBC.
"This oversight had the potential to erode the exceptionally strong levels of trust that the public would have invested in a factual film from the broadcaster about the conflict in Gaza."
The programme was withdrawn from the online platform in last February after the narrator's personal associations came to light, and in July an corporation's own inquiry determined it violated the corporation's journalistic standards on accuracy.
A corporation official said: "The authority's determination is in agreement with the conclusions of the corporation's inquiry, that there was a significant failing in the documentary in relation to the BBC's Editorial Guidelines on truthfulness, which reflects regulation 2.2 of the authority's broadcasting regulations.
"We issued an apology for this and we comply with Ofcom's decision in its entirety. We will adhere to the sanction as soon as the timing and language are finalised."
