The British broadcaster engaged in a "major breach" of industry standards by not revealing that the voice of a programme about Gaza was the son of a Hamas official, according to British broadcasting authority Ofcom.
An probe by the media regulator into Gaza: How to Survive a Warzone has found that the film was "materially misleading".
The BBC's director general had earlier expressed regret, saying there had been "a serious error in relation to accuracy".
Ofcom has instructed the BBC to broadcast a prime-time announcement about its decisions.
"As this represents a serious breach of our rules, we are directing the corporation to transmit a statement of our determinations against it on the BBC's second channel at 9pm, with a timing to be confirmed," the regulator stated.
'Potential to Damage Credibility'
The authority's announcement said: "Our investigation concluded that the programme's failure to disclose that the voice's parent served in a post in the Hamas-administered government was substantially inaccurate.
"This implied that the public did not have critical information which may have been very significant to their assessment of the voice and the information he provided.
"Confidence is at the center of the bond between a broadcaster and its audience, especially for a public service broadcaster such as the British Broadcasting Corporation.
"This oversight had the possibility to undermine the significantly high amounts of confidence that viewers would have invested in a BBC factual programme about the Gaza conflict."
The programme was withdrawn from the BBC's streaming service in February after the boy's personal associations were revealed, and in this past July an broadcaster's internal assessment determined it violated the organization's content policies on truthfulness.
A BBC spokesperson commented: "The Ofcom ruling is in accordance with the results of the internal assessment, that there was a significant failing in the programme in relation to the broadcaster's journalistic policies on truthfulness, which corresponds to Rule 2.2 of the authority's broadcasting regulations.
"We have apologised for this and we agree with the regulator's ruling in complete. We will comply with the penalty as soon as the timing and wording are confirmed."
