The BBC engaged in a "serious breach" of media regulations by not revealing that the narrator of a documentary about Gaza was the son of a Hamas administrator, as determined by regulatory body Ofcom.
An investigation by the broadcasting watchdog into Gaza: How to Survive a Warzone has found that the programme was "substantially inaccurate".
The head of the BBC had already issued an apology, stating there had been "a significant failing in relation to accuracy".
Ofcom has instructed the BBC to transmit a peak-time declaration about its decisions.
"Since this amounts to a serious breach of our code, we are directing the corporation to transmit a message of our determinations against it on BBC Two at 9pm, with a date to be finalised," the statement read.
'Risk to Damage Credibility'
The regulator's announcement said: "The inquiry we conducted found that the film's failure to disclose that the presenter's parent served in a role in the Hamas-controlled authority was substantially inaccurate.
"Consequently that the audience did not have critical information which may have been very significant to their judgment of the presenter and the details he shared.
"Trust is at the heart of the bond between a television network and its viewers, particularly for a national broadcasting corporation such as the BBC.
"This failing had the potential to undermine the significantly high degrees of credibility that audiences would have placed in a documentary produced by the BBC about the conflict in Gaza."
The film was removed from the BBC's streaming service in February after the presenter's personal associations emerged, and in the month of July an internal BBC review concluded it infringed the organization's editorial guidelines on factual correctness.
A corporation official commented: "The regulator's decision is in accordance with the conclusions of the corporation's inquiry, that there was a significant failing in the programme in relation to the BBC's Editorial Guidelines on truthfulness, which corresponds to Rule 2.2 of Ofcom's Broadcasting Code.
"We expressed regret for this and we agree with the regulator's ruling in full. We will comply with the sanction as soon as the timing and wording are finalised."
