The public service broadcaster was found to have committed a "major breach" of industry standards by not revealing that the narrator of a film about the Gaza situation was the child of a Hamas representative, according to regulatory body Ofcom.
An inquiry by Ofcom into Gaza: How to Survive a Warzone has determined that the film was "substantially inaccurate".
The head of the BBC had already issued an apology, saying there had been "a serious error in relation to truthfulness".
Ofcom has directed the broadcaster to air a peak-time announcement about its findings.
"As this represents a significant violation of our rules, we are directing the corporation to broadcast a message of our determinations against it on the BBC's second channel at 21:00, with a schedule to be finalised," it said.
'Risk to Undermine Credibility'
The watchdog's statement said: "Our investigation determined that the film's omission to reveal that the voice's parent occupied a post in the Hamas-run government was materially misleading.
"It meant that the audience did not have essential details which may have been very significant to their judgment of the voice and the details he provided.
"Credibility is at the heart of the connection between a broadcaster and its viewers, notably for a national broadcasting corporation such as the public broadcaster.
"This error had the potential to damage the significantly high levels of trust that the public would have put in a documentary produced by the BBC about the Gaza conflict."
The programme was removed from the BBC's streaming service in February after the narrator's familial connections were revealed, and in this past July an corporation's own inquiry determined it infringed the corporation's content policies on truthfulness.
A BBC spokesperson commented: "The regulator's decision is in line with the findings of Peter Johnston's review, that there was a serious error in the film in relation to the broadcaster's journalistic policies on truthfulness, which aligns with Rule 2.2 of Ofcom's Broadcasting Code.
"We issued an apology for this and we agree with the authority's determination in complete. We will adhere to the sanction as soon as the timing and wording are finalised."
