The British broadcaster engaged in a "major breach" of media regulations by omitting to mention that the voice of a programme about the Gaza conflict was the offspring of a Hamas official, as ruled by UK media regulator Ofcom.
An inquiry by Ofcom into Gaza: How to Survive a Warzone has concluded that the film was "materially misleading".
The BBC's director general had earlier expressed regret, saying there had been "a significant failing in relation to accuracy".
Ofcom has ordered the BBC to transmit a prime-time declaration about its findings.
"As this represents a serious breach of our regulations, we are instructing the corporation to transmit a message of our findings against it on BBC Two at 9pm, with a schedule to be finalised," it said.
'Potential to Erode Confidence'
The regulator's report said: "Our investigation found that the programme's lack of disclosure that the voice's male guardian occupied a position in the Hamas-run authority was substantially inaccurate.
"It meant that the audience did not have vital facts which may have been highly relevant to their assessment of the presenter and the content he presented.
"Confidence is at the heart of the connection between a media organization and its public, notably for a public service broadcaster such as the public broadcaster.
"This oversight had the risk to damage the very considerable amounts of trust that the public would have put in a documentary produced by the BBC about the Gaza conflict."
The documentary was withdrawn from the online platform in last February after the boy's personal associations came to light, and in July an broadcaster's internal assessment found it infringed the corporation's editorial guidelines on accuracy.
A BBC spokesperson stated: "The authority's determination is in agreement with the results of the internal assessment, that there was a significant failing in the film in relation to the corporation's content standards on accuracy, 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 its entirety. We will comply with the sanction as soon as the date and wording are confirmed."
