The British broadcaster committed a "serious breach" of broadcasting rules by not revealing that the presenter of a documentary about the Gaza situation was the offspring of a Hamas administrator, as ruled by UK media regulator Ofcom.
An probe by the media regulator into Gaza: How to Survive a Warzone has concluded that the programme was "significantly deceptive".
The head of the BBC had earlier expressed regret, noting there had been "a significant failing in relation to truthfulness".
The regulator has instructed the corporation to air a peak-time announcement about its findings.
"Since this amounts to a serious breach of our rules, we are instructing the corporation to transmit a announcement of our conclusions against it on BBC Two at nine o'clock in the evening, with a timing to be finalised," the statement read.
'Possibility to Undermine Confidence'
The authority's statement said: "Our probe found that the documentary's omission to reveal that the voice's male guardian held a post in the Hamas-administered authority was materially misleading.
"This implied that the audience did not have essential details which may have been extremely pertinent to their evaluation of the presenter and the content he provided.
"Credibility is at the center of the bond between a media organization and its public, notably for a public service broadcaster such as the BBC.
"This oversight had the risk to damage the very considerable levels of confidence that the public would have invested in a factual film from the broadcaster about the conflict in Gaza."
The film was pulled from the online platform in February after the narrator's family links were revealed, and in July an internal BBC review found it breached the organization's journalistic standards on truthfulness.
A corporation official said: "The regulator's decision is in agreement with the results of Peter Johnston's review, that there was a serious error in the programme in relation to the broadcaster's journalistic policies on truthfulness, which corresponds to clause 2.2 of the regulator's media standards.
"We have apologised for this and we accept the authority's determination in full. We will comply with the penalty as soon as the schedule and wording are determined."
