The BBC was found to have committed a "serious breach" of industry standards by failing to disclose that the voice of a film about Gaza was the child of a Hamas official, as ruled by regulatory body Ofcom.
An probe by the broadcasting watchdog into Gaza: How to Survive a Warzone has concluded that the film was "significantly deceptive".
The head of the BBC had already issued an apology, noting there had been "a significant failing in relation to accuracy".
Ofcom has directed the BBC to broadcast a peak-time statement about its conclusions.
"As this represents a serious breach of our code, we are ordering the broadcaster to transmit a announcement of our conclusions against it on BBC2 at nine o'clock in the evening, with a schedule to be determined," the statement read.
'Possibility to Erode Trust'
The regulator's report declared: "Our investigation concluded that the programme's lack of disclosure that the presenter's parent served in a role in the Hamas-controlled government was materially misleading.
"This implied that the public did not have vital facts which may have been highly relevant to their judgment of the voice and the information he provided.
"Confidence is at the core of the relationship between a media organization and its public, particularly for a state-funded media outlet such as the BBC.
"This oversight had the possibility to erode the very considerable levels of credibility that viewers would have placed in a BBC factual programme about the conflict in Gaza."
The film was withdrawn from iPlayer in February after the presenter's personal associations emerged, and in July an broadcaster's internal assessment determined it breached the broadcaster's editorial guidelines on truthfulness.
A representative for the broadcaster said: "The Ofcom ruling is in accordance with the results of Peter Johnston's review, that there was a significant failing in the film in relation to the BBC's Editorial Guidelines on truthfulness, which aligns with Rule 2.2 of the regulator's media standards.
"We expressed regret for this and we comply with Ofcom's decision in complete. We will follow the penalty as soon as the date and wording are determined."
