The British broadcaster engaged in a "serious breach" of industry standards by failing to disclose that the voice of a programme about Gaza was the child of a Hamas administrator, as determined by British broadcasting authority Ofcom.
An inquiry by the media regulator into the programme Gaza: How to Survive a Warzone has found that the documentary was "substantially inaccurate".
The BBC's director general had previously apologised, saying there had been "a serious error in relation to accuracy".
The regulator has instructed the broadcaster to transmit a prime-time announcement about its conclusions.
"As this represents a serious breach of our rules, we are instructing the corporation to air a announcement of our findings against it on BBC2 at nine o'clock in the evening, with a date to be confirmed," it said.
'Potential to Undermine Trust'
The regulator's report stated: "Our probe concluded that the film's omission to reveal that the narrator's parent served in a position in the Hamas-administered administration was materially misleading.
"Consequently that the audience did not have vital facts which may have been very significant to their evaluation of the narrator and the content he provided.
"Trust is at the core of the bond between a broadcaster and its public, especially for a state-funded media outlet such as the public broadcaster.
"This failing had the risk to erode the very considerable amounts of trust that audiences would have placed in a factual film from the broadcaster about the Israel-Gaza war."
The documentary was removed from iPlayer in the month of February after the presenter's family links emerged, and in this past July an broadcaster's internal assessment concluded it violated the organization's editorial guidelines on truthfulness.
A BBC spokesperson said: "The regulator's decision is in line with the results of Peter Johnston's review, that there was a significant failing in the documentary in relation to the corporation's content standards on truthfulness, which corresponds to regulation 2.2 of the authority's broadcasting regulations.
"We issued an apology for this and we accept the authority's determination in full. We will follow the penalty as soon as the schedule and wording are finalised."
