The public service broadcaster committed a "significant breach" of media regulations by not revealing that the presenter of a documentary about Gaza was the child of a Hamas administrator, as ruled by British broadcasting authority Ofcom.
An investigation by Ofcom into the programme Gaza: How to Survive a Warzone has found that the documentary was "significantly deceptive".
The head of the BBC had earlier expressed regret, saying there had been "a major oversight in relation to accuracy".
The authority has directed the BBC to air a peak-time declaration about its conclusions.
"Since this amounts to a significant violation of our rules, we are instructing the corporation to air a message of our conclusions against it on BBC Two at 21:00, with a date to be finalised," it said.
'Potential to Erode Credibility'
The watchdog's statement said: "The inquiry we conducted determined that the documentary's lack of disclosure that the narrator's father served in a position in the Hamas-run government was substantially inaccurate.
"It meant that the public did not have vital facts which may have been highly relevant to their assessment of the presenter and the information he presented.
"Confidence is at the heart of the connection between a television network and its viewers, particularly for a state-funded media outlet such as the public broadcaster.
"This oversight had the possibility to damage the very considerable levels of credibility that viewers would have placed in a documentary produced by the BBC about the Israel-Gaza war."
The film was pulled from the BBC's streaming service in last February after the narrator's familial connections emerged, and in the month of July an internal BBC review determined it breached the organization's editorial guidelines on accuracy.
A BBC spokesperson stated: "The authority's determination is in line with the conclusions of the corporation's inquiry, that there was a serious error in the documentary in relation to the corporation's content standards on factual correctness, which aligns with Rule 2.2 of the authority's broadcasting regulations.
"We have apologised for this and we accept Ofcom's decision in its entirety. We will follow the penalty as soon as the timing and language are determined."