The BBC was found to have committed a "major breach" of broadcasting rules by failing to disclose that the presenter of a programme about Gaza was the offspring of a Hamas representative, according to regulatory body Ofcom.
An inquiry by Ofcom into Gaza: How to Survive a Warzone has determined that the documentary was "substantially inaccurate".
The BBC's director general had already issued an apology, saying there had been "a major oversight in relation to truthfulness".
Ofcom has directed the BBC to broadcast a prime-time declaration about its findings.
"As this represents a serious breach of our regulations, we are instructing the broadcaster to broadcast a announcement of our conclusions against it on BBC Two at 21:00, with a schedule to be finalised," the regulator stated.
'Risk to Undermine Credibility'
The watchdog's report said: "The inquiry we conducted determined that the film's failure to disclose that the voice's male guardian held a role in the Hamas-administered government was significantly deceptive.
"This implied that the public did not have essential details which may have been highly relevant to their judgment of the voice and the information he presented.
"Confidence is at the core of the relationship between a media organization and its public, especially for a state-funded media outlet such as the public broadcaster.
"This error had the risk to erode the exceptionally strong levels of trust that viewers would have invested in a documentary produced by the BBC about the Israel-Gaza war."
The film was removed from the BBC's streaming service in the month of February after the presenter's family links were revealed, and in July an corporation's own inquiry concluded it infringed the broadcaster's content policies on accuracy.
A representative for the broadcaster commented: "The authority's determination is in agreement with the conclusions of Peter Johnston's review, that there was a serious error in the programme in relation to the corporation's content standards on factual correctness, which aligns with regulation 2.2 of Ofcom's Broadcasting Code.
"We issued an apology for this and we comply with the authority's determination in full. We will follow the sanction as soon as the date and language are confirmed."
