The public service broadcaster engaged in a "major breach" of media regulations by failing to disclose that the narrator of a film about the Gaza conflict was the son of a Hamas official, as determined by British broadcasting authority Ofcom.
An probe by the media regulator into Gaza: How to Survive a Warzone has found that the film was "substantially inaccurate".
The BBC's director general had already issued an apology, noting there had been "a major oversight in relation to truthfulness".
Ofcom has directed the BBC to transmit a prime-time declaration about its findings.
"As this represents a serious breach of our rules, we are instructing the BBC to transmit a statement of our findings against it on BBC2 at 21:00, with a schedule to be determined," the statement read.
'Potential to Damage Confidence'
The watchdog's statement stated: "Our investigation concluded that the documentary's omission to reveal that the presenter's father served in a position in the Hamas-run authority was substantially inaccurate.
"Consequently that the public did not have essential details which may have been highly relevant to their judgment of the voice and the details he presented.
"Credibility is at the core of the connection between a media organization and its audience, especially for a national broadcasting corporation such as the public broadcaster.
"This error had the possibility to undermine the significantly high levels of credibility that the public would have invested in a documentary produced by the BBC about the Gaza conflict."
The programme was withdrawn from the BBC's streaming service in February after the presenter's personal associations were revealed, and in the month of July an corporation's own inquiry concluded it breached the corporation's journalistic standards on accuracy.
A BBC spokesperson said: "The authority's determination is in accordance with the findings of Peter Johnston's review, that there was a serious error in the documentary in relation to the corporation's content standards on truthfulness, which reflects clause 2.2 of Ofcom's Broadcasting Code.
"We issued an apology for this and we comply with Ofcom's decision in complete. We will follow the directive as soon as the schedule and language are finalised."
