The public service broadcaster engaged in a "significant breach" of industry standards by not revealing that the presenter of a film about Gaza was the offspring of a Hamas administrator, according to regulatory body Ofcom.
An probe by the broadcasting watchdog into Gaza: How to Survive a Warzone has concluded that the programme was "significantly deceptive".
The head of the BBC had previously apologised, saying there had been "a significant failing in relation to truthfulness".
The authority has directed the BBC to air a prime-time announcement about its findings.
"As this represents a serious breach of our regulations, we are instructing the BBC to air a message of our determinations against it on the BBC's second channel at nine o'clock in the evening, with a timing to be finalised," the statement read.
'Potential to Damage Confidence'
The watchdog's announcement stated: "The inquiry we conducted concluded that the documentary's omission to reveal that the narrator's parent served in a position in the Hamas-controlled government was substantially inaccurate.
"This implied that the audience did not have vital facts which may have been very significant to their judgment of the presenter and the details he provided.
"Confidence is at the core of the connection between a television network and its viewers, notably for a public service broadcaster such as the BBC.
"This failing had the possibility to damage the exceptionally strong amounts of trust that audiences would have put in a factual film from the broadcaster about the Gaza conflict."
The documentary was pulled from iPlayer in the month of February after the narrator's family links emerged, and in July an broadcaster's internal assessment found it violated the organization's journalistic standards on accuracy.
A BBC spokesperson said: "The regulator's decision is in accordance with the findings of Peter Johnston's review, that there was a serious error in the programme in relation to the corporation's content standards on truthfulness, which reflects clause 2.2 of the regulator's media standards.
"We expressed regret for this and we comply with Ofcom's decision in full. We will follow the penalty as soon as the date and language are confirmed."
