The BBC engaged in a "serious breach" of media regulations by omitting to mention that the narrator of a programme about the Gaza conflict was the child of a Hamas official, as determined by regulatory body Ofcom.
An probe by the broadcasting watchdog into the programme Gaza: How to Survive a Warzone has concluded that the film was "substantially inaccurate".
The head of the BBC had previously apologised, saying there had been "a serious error in relation to truthfulness".
The regulator has instructed the BBC to air a prime-time declaration about its conclusions.
"Since this amounts to a serious breach of our regulations, we are directing the corporation to transmit a message of our findings against it on the BBC's second channel at 9pm, with a schedule to be determined," the statement read.
'Risk to Erode Confidence'
The regulator's announcement said: "Our probe found that the documentary's failure to disclose that the presenter's male guardian served in a post in the Hamas-administered government was materially misleading.
"This implied that the public did not have vital facts which may have been highly relevant to their assessment of the presenter and the information he presented.
"Credibility is at the core of the bond between a broadcaster and its audience, notably for a state-funded media outlet such as the British Broadcasting Corporation.
"This failing had the potential to erode the very considerable amounts of credibility that the public would have invested in a documentary produced by the BBC about the Israel-Gaza war."
The programme was pulled from the online platform in the month of February after the presenter's family links were revealed, and in July an internal BBC review found it breached the broadcaster's journalistic standards on accuracy.
A corporation official commented: "The authority's determination is in line with the conclusions of Peter Johnston's review, that there was a major oversight in the documentary in relation to the BBC's Editorial Guidelines on truthfulness, which aligns with clause 2.2 of Ofcom's Broadcasting Code.
"We have apologised for this and we accept Ofcom's decision in its entirety. We will adhere to the penalty as soon as the date and language are determined."
