The public service broadcaster engaged in a "major breach" of broadcasting rules by not revealing that the voice of a documentary about Gaza was the offspring of a Hamas administrator, as determined by British broadcasting authority Ofcom.
An investigation by the broadcasting watchdog into the programme Gaza: How to Survive a Warzone has concluded that the programme was "substantially inaccurate".
The BBC's director general had already issued an apology, noting there had been "a serious error in relation to accuracy".
The authority has ordered the BBC to air a evening announcement about its conclusions.
"Since this amounts to a significant violation of our regulations, we are directing the corporation to transmit a message of our conclusions against it on BBC2 at 21:00, with a timing to be confirmed," it said.
'Potential to Undermine Trust'
The authority's announcement said: "Our probe determined that the film's lack of disclosure that the voice's parent occupied a role in the Hamas-administered government was substantially inaccurate.
"Consequently that the audience did not have essential details which may have been very significant to their judgment of the voice and the information he presented.
"Trust is at the heart of the connection between a broadcaster and its viewers, especially for a national broadcasting corporation such as the public broadcaster.
"This error had the possibility to damage the significantly high degrees of credibility that the public would have put in a factual film from the broadcaster about the conflict in Gaza."
The documentary was withdrawn from iPlayer in February after the boy's familial connections came to light, and in July an broadcaster's internal assessment concluded it infringed the corporation's journalistic standards on accuracy.
A representative for the broadcaster said: "The regulator's decision is in line with the results of the corporation's inquiry, that there was a serious error in the programme in relation to the BBC's Editorial Guidelines on truthfulness, which reflects clause 2.2 of the authority's broadcasting regulations.
"We issued an apology for this and we agree with the regulator's ruling in its entirety. We will adhere to the penalty as soon as the schedule and language are finalised."
