The BBC engaged in a "major breach" of broadcasting rules by omitting to mention that the voice of a film about Gaza was the son of a Hamas official, as determined by British broadcasting authority Ofcom.
An investigation by the broadcasting watchdog into Gaza: How to Survive a Warzone has concluded that the film was "substantially inaccurate".
The BBC's director general had previously apologised, stating there had been "a major oversight in relation to truthfulness".
The authority has instructed the broadcaster to broadcast a prime-time announcement about its decisions.
"Given this constitutes a significant violation of our rules, we are directing the corporation to air a announcement of our conclusions against it on the BBC's second channel at nine o'clock in the evening, with a schedule to be confirmed," the regulator stated.
'Potential to Erode Trust'
The watchdog's statement stated: "Our probe concluded that the documentary's omission to reveal that the presenter's male guardian held a role in the Hamas-run authority was substantially inaccurate.
"This implied that the audience did not have vital facts which may have been extremely pertinent to their assessment of the presenter and the information he shared.
"Credibility is at the heart of the connection between a media organization and its viewers, especially for a public service broadcaster such as the BBC.
"This oversight had the possibility to damage the very considerable amounts of trust that audiences would have invested in a factual film from the broadcaster about the conflict in Gaza."
The documentary was withdrawn from the BBC's streaming service in the month of February after the presenter's familial connections came to light, and in July an internal BBC review concluded it violated the corporation's editorial guidelines on accuracy.
A corporation official stated: "The authority's determination is in line with the conclusions of Peter Johnston's review, that there was a major oversight in the documentary 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 accept the regulator's ruling in full. We will comply with the sanction as soon as the timing and wording are determined."
