The BBC committed a "significant breach" of media regulations by omitting to mention that the voice of a film about the Gaza situation was the child of a Hamas representative, according to UK media regulator Ofcom.
An investigation by the media regulator into the programme Gaza: How to Survive a Warzone has determined that the documentary was "materially misleading".
The BBC's director general had previously apologised, saying there had been "a significant failing in relation to factual correctness".
The authority has directed the broadcaster to transmit a peak-time declaration about its decisions.
"Given this constitutes a significant violation of our regulations, we are instructing the corporation to air a announcement of our conclusions against it on BBC Two at 21:00, with a date to be determined," the statement read.
'Possibility to Erode Credibility'
The watchdog's announcement said: "Our probe concluded that the programme's omission to reveal that the narrator's male guardian held a post in the Hamas-administered government was substantially inaccurate.
"It meant that the public did not have essential details which may have been very significant to their assessment of the voice and the content he shared.
"Credibility is at the heart of the connection between a broadcaster and its audience, especially for a national broadcasting corporation such as the British Broadcasting Corporation.
"This oversight had the possibility to damage the significantly high levels of trust that audiences would have placed in a BBC factual programme about the Israel-Gaza war."
The programme was withdrawn from the BBC's streaming service in last February after the presenter's personal associations were revealed, and in this past July an broadcaster's internal assessment found it violated the broadcaster's editorial guidelines on truthfulness.
A corporation official commented: "The authority's determination is in line with the results of the internal assessment, that there was a significant failing in the film in relation to the broadcaster's journalistic policies on truthfulness, which aligns with Rule 2.2 of the regulator's media standards.
"We expressed regret for this and we comply with the regulator's ruling in its entirety. We will follow the sanction as soon as the timing and wording are finalised."
