The BBC committed a "major breach" of media regulations by not revealing that the narrator of a film about the Gaza conflict was the offspring of a Hamas official, as ruled by UK media regulator Ofcom.
An inquiry by Ofcom into the programme Gaza: How to Survive a Warzone has found that the documentary was "significantly deceptive".
The BBC's director general had already issued an apology, saying there had been "a significant failing in relation to factual correctness".
The authority has directed the broadcaster to air a prime-time statement about its findings.
"Since this amounts to a serious breach of our rules, we are directing the BBC to broadcast a message of our findings against it on the BBC's second channel at 21:00, with a schedule to be determined," the regulator stated.
'Risk to Undermine Trust'
The regulator's statement said: "Our investigation determined that the film's omission to reveal that the voice's male guardian held a position in the Hamas-controlled government was significantly deceptive.
"It meant that the viewers did not have essential details which may have been highly relevant to their judgment of the narrator and the details he presented.
"Trust is at the core of the bond between a media organization and its audience, especially for a national broadcasting corporation such as the British Broadcasting Corporation.
"This oversight had the potential to undermine the significantly high levels of credibility that audiences would have placed in a BBC factual programme about the Israel-Gaza war."
The documentary was withdrawn from iPlayer in February after the presenter's personal associations emerged, and in July an internal BBC review found it breached the broadcaster's journalistic standards on truthfulness.
A corporation official stated: "The Ofcom ruling is in accordance with the results of Peter Johnston's review, that there was a significant failing in the documentary in relation to the corporation's content standards on accuracy, which corresponds to Rule 2.2 of the regulator's media standards.
"We expressed regret for this and we comply with the regulator's ruling in its entirety. We will follow the directive as soon as the timing and wording are determined."
