The public service broadcaster committed a "significant breach" of media regulations by not revealing that the presenter of a programme about the Gaza conflict was the son of a Hamas representative, as determined by UK media regulator Ofcom.
An probe by the media regulator into the programme Gaza: How to Survive a Warzone has determined that the programme was "materially misleading".
The BBC's director general had already issued an apology, saying there had been "a serious error in relation to accuracy".
Ofcom has ordered the corporation to transmit a prime-time announcement about its conclusions.
"Since this amounts to a significant violation of our regulations, we are instructing the BBC to air a message of our determinations against it on BBC Two at 21:00, with a date to be finalised," it said.
'Possibility to Erode Trust'
The watchdog's statement said: "The inquiry we conducted determined that the programme's failure to disclose that the presenter's male guardian occupied a role in the Hamas-administered administration was materially misleading.
"Consequently that the audience did not have vital facts which may have been very significant to their evaluation of the narrator and the content he shared.
"Trust is at the center of the bond between a broadcaster and its audience, particularly for a national broadcasting corporation such as the British Broadcasting Corporation.
"This error had the risk to damage the very considerable amounts of confidence that audiences would have placed in a factual film from the broadcaster about the Gaza conflict."
The film was removed from the BBC's streaming service in February after the boy's personal associations came to light, and in the month of July an internal BBC review concluded it breached the broadcaster's content policies on truthfulness.
A representative for the broadcaster commented: "The regulator's decision is in accordance with the results of the corporation's inquiry, that there was a significant failing in the documentary in relation to the corporation's content standards on factual correctness, which reflects clause 2.2 of the regulator's media standards.
"We issued an apology for this and we agree with the regulator's ruling in full. We will follow the sanction as soon as the timing and wording are finalised."
