The BBC engaged in a "major breach" of industry standards by not revealing that the narrator of a documentary about the Gaza conflict was the son of a Hamas official, according to British broadcasting authority Ofcom.
An investigation by the broadcasting watchdog into Gaza: How to Survive a Warzone has found that the programme was "substantially inaccurate".
The chief executive of the broadcaster had previously apologised, saying there had been "a serious error in relation to accuracy".
The regulator has ordered the BBC to broadcast a peak-time announcement about its conclusions.
"Since this amounts to a serious breach of our rules, we are directing the broadcaster to air a statement of our determinations against it on BBC2 at nine o'clock in the evening, with a timing to be determined," the regulator stated.
'Possibility to Damage Credibility'
The regulator's announcement said: "Our investigation determined that the film's failure to disclose that the narrator's parent occupied a position in the Hamas-administered authority was materially misleading.
"It meant that the public did not have essential details which may have been very significant to their judgment of the presenter and the details he presented.
"Credibility is at the core of the bond between a broadcaster and its public, especially for a national broadcasting corporation such as the British Broadcasting Corporation.
"This error had the risk to damage the exceptionally strong levels of credibility that audiences would have put in a BBC factual programme about the conflict in Gaza."
The programme was withdrawn from the online platform in the month of February after the presenter's familial connections were revealed, and in the month of July an broadcaster's internal assessment concluded it infringed the broadcaster's journalistic standards on factual correctness.
A BBC spokesperson said: "The Ofcom ruling is in accordance with the findings of the corporation's inquiry, that there was a major oversight in the programme in relation to the broadcaster's journalistic policies on truthfulness, which reflects regulation 2.2 of Ofcom's Broadcasting Code.
"We expressed regret for this and we comply with the regulator's ruling in full. We will follow the penalty as soon as the date and language are determined."
