The public service broadcaster committed a "serious breach" of industry standards by omitting to mention that the voice of a programme about Gaza was the son of a Hamas official, according to British broadcasting authority Ofcom.
An inquiry by the media regulator into the programme Gaza: How to Survive a Warzone has determined that the programme was "materially misleading".
The BBC's director general had already issued an apology, stating there had been "a serious error in relation to accuracy".
Ofcom has instructed the broadcaster to broadcast a prime-time announcement about its conclusions.
"Since this amounts to a significant violation of our rules, we are directing the BBC to transmit a statement of our findings against it on the BBC's second channel at nine o'clock in the evening, with a timing to be confirmed," the statement read.
'Risk to Undermine Trust'
The watchdog's report said: "Our investigation found that the programme's lack of disclosure that the presenter's male guardian served in a role in the Hamas-run authority was substantially inaccurate.
"It meant that the public did not have vital facts which may have been very significant to their judgment of the voice and the details he shared.
"Credibility is at the core of the bond between a television network and its viewers, especially for a state-funded media outlet such as the public broadcaster.
"This failing had the risk to erode the significantly high degrees of confidence that the public would have placed in a factual film from the broadcaster about the Israel-Gaza war."
The documentary was withdrawn from iPlayer in last February after the narrator's personal associations were revealed, and in the month of July an internal BBC review concluded it breached the corporation's editorial guidelines on accuracy.
A BBC spokesperson commented: "The regulator's decision is in line with the conclusions of the internal assessment, that there was a serious error in the programme in relation to the corporation's content standards on accuracy, which aligns with regulation 2.2 of the regulator's media standards.
"We issued an apology for this and we accept the regulator's ruling in full. We will comply with the penalty as soon as the timing and language are confirmed."
