The BBC committed a "serious breach" of industry standards by failing to disclose that the voice of a programme about the Gaza situation was the child of a Hamas representative, as determined by regulatory body Ofcom.
An inquiry by the media regulator into Gaza: How to Survive a Warzone has determined that the programme was "materially misleading".
The BBC's director general had previously apologised, noting there had been "a significant failing in relation to accuracy".
Ofcom has ordered the corporation to broadcast a evening announcement about its decisions.
"As this represents a serious breach of our rules, we are directing the corporation to transmit a message of our conclusions against it on BBC Two at 21:00, with a date to be determined," the statement read.
'Possibility to Damage Trust'
The watchdog's announcement declared: "Our probe determined that the film's omission to reveal that the voice's male guardian served in a position in the Hamas-controlled government was materially misleading.
"This implied that the public did not have essential details which may have been very significant to their assessment of the narrator and the details he provided.
"Confidence is at the heart of the relationship between a broadcaster and its viewers, especially for a national broadcasting corporation such as the public broadcaster.
"This oversight had the risk to erode the exceptionally strong levels of trust that the public would have invested in a factual film from the broadcaster about the Israel-Gaza war."
The documentary was pulled from iPlayer in February after the presenter's family links emerged, and in July an corporation's own inquiry determined it breached the broadcaster's journalistic standards on truthfulness.
A corporation official stated: "The regulator's decision is in agreement with the conclusions of the internal assessment, that there was a significant failing in the programme in relation to the corporation's content standards on factual correctness, which corresponds to clause 2.2 of the authority's broadcasting regulations.
"We issued an apology for this and we comply with the regulator's ruling in complete. We will follow the sanction as soon as the timing and language are finalised."
