The BBC engaged in a "significant breach" of broadcasting rules by omitting to mention that the voice of a documentary about the Gaza conflict was the son of a Hamas administrator, as ruled by regulatory body Ofcom.
An investigation by the media regulator into Gaza: How to Survive a Warzone has concluded that the film was "materially misleading".
The BBC's director general had already issued an apology, stating there had been "a significant failing in relation to accuracy".
The regulator has instructed the broadcaster to broadcast a peak-time announcement about its findings.
"Since this amounts to a significant violation of our regulations, we are ordering the corporation to broadcast a message of our conclusions against it on BBC Two at 21:00, with a schedule to be finalised," the regulator stated.
'Risk to Damage Credibility'
The watchdog's statement stated: "The inquiry we conducted concluded that the programme's lack of disclosure that the presenter's parent held a post in the Hamas-controlled government was materially misleading.
"This implied that the audience did not have essential details which may have been highly relevant to their judgment of the voice and the information he presented.
"Confidence is at the center of the connection between a broadcaster and its audience, particularly for a public service broadcaster such as the British Broadcasting Corporation.
"This failing had the risk to undermine the very considerable levels of credibility that audiences would have placed in a BBC factual programme about the conflict in Gaza."
The programme was pulled from the BBC's streaming service in last February after the presenter's familial connections were revealed, and in July an broadcaster's internal assessment found it infringed the organization's editorial guidelines on truthfulness.
A representative for the broadcaster stated: "The authority's determination is in agreement with the results of the internal assessment, that there was a major oversight in the film in relation to the corporation's content standards on accuracy, which corresponds to clause 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 adhere to the penalty as soon as the date and wording are confirmed."
