The BBC committed a "significant breach" of media regulations by not revealing that the narrator of a programme about Gaza was the offspring of a Hamas representative, as ruled by UK media regulator Ofcom.
An probe by the broadcasting watchdog into Gaza: How to Survive a Warzone has concluded that the film was "substantially inaccurate".
The head of the BBC had earlier expressed regret, saying there had been "a major oversight in relation to accuracy".
The regulator has directed the corporation to air a evening declaration about its findings.
"As this represents a serious breach of our regulations, we are directing the BBC to air a message of our findings against it on BBC2 at 21:00, with a timing to be finalised," the statement read.
'Potential to Undermine Trust'
The regulator's report stated: "Our investigation found that the documentary's lack of disclosure that the presenter's father occupied a post in the Hamas-controlled government was substantially inaccurate.
"It meant that the audience did not have essential details which may have been very significant to their judgment of the narrator and the information he presented.
"Confidence is at the core of the relationship 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 exceptionally strong levels of credibility that audiences would have placed in a BBC factual programme about the conflict in Gaza."
The documentary was pulled from iPlayer in February after the boy's family links emerged, and in July an broadcaster's internal assessment concluded it breached the corporation's content policies on accuracy.
A corporation official stated: "The regulator's decision is in line with the conclusions 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 the authority's broadcasting regulations.
"We have apologised for this and we accept the regulator's ruling in full. We will comply with the directive as soon as the date and language are confirmed."
