The BBC was found to have committed a "serious breach" of industry standards by not revealing that the presenter of a programme about the Gaza conflict was the son of a Hamas administrator, as ruled by regulatory body Ofcom.
An probe by the media regulator into Gaza: How to Survive a Warzone has determined that the programme was "significantly deceptive".
The BBC's director general had already issued an apology, noting there had been "a serious error in relation to truthfulness".
Ofcom has directed the BBC to broadcast a peak-time announcement about its conclusions.
"Since this amounts to a major infringement of our regulations, we are ordering the corporation to air a statement of our determinations against it on BBC Two at nine o'clock in the evening, with a timing to be determined," the statement read.
'Potential to Damage Credibility'
The regulator's report declared: "Our probe determined that the film's failure to disclose that the narrator's father held a post in the Hamas-controlled authority was significantly deceptive.
"Consequently that the viewers did not have critical information which may have been very significant to their assessment of the presenter and the content he shared.
"Confidence is at the center of the relationship between a television network and its public, particularly for a state-funded media outlet such as the public broadcaster.
"This error had the risk to undermine the very considerable degrees of credibility that audiences would have put in a documentary produced by the BBC about the Gaza conflict."
The documentary was withdrawn from the BBC's streaming service in last February after the presenter's personal associations were revealed, and in this past July an broadcaster's internal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 concluded it breached the corporation's journalistic standards on factual correctness.
A corporation official commented: "The authority's determination is in agreement with the conclusions of the corporation's inquiry, that there was a significant failing in the documentary in relation to the corporation's content standards on accuracy, which corresponds to regulation 2.2 of the regulator's media standards.
"We expressed regret for this and we accept Ofcom's decision in its entirety. We will follow the penalty as soon as the schedule and wording are finalised."
