The BBC committed a "serious breach" of broadcasting rules by omitting to mention that the voice of a documentary about the Gaza conflict was the child of a Hamas official, as determined by British broadcasting authority Ofcom.
An inquiry by the media regulator into the programme Gaza: How to Survive a Warzone has found that the film was "significantly deceptive".
The chief executive of the broadcaster had previously apologised, noting there had been "a major oversight in relation to truthfulness".
Ofcom has ordered the broadcaster to transmit a prime-time declaration about its findings.
"As this represents a major infringement of our regulations, we are ordering the broadcaster to air a message of our findings against it on BBC Two at nine o'clock in the evening, with a date to be confirmed," the regulator stated.
'Risk to Damage Confidence'
The watchdog's announcement declared: "Our probe found that the documentary's lack of disclosure that the presenter's male guardian occupied a role in the Hamas-run government was significantly deceptive.
"It meant that the public did not have critical information which may have been very significant to their judgment of the presenter and the content he shared.
"Trust is at the heart of the bond between a television network and its public, especially for a public service broadcaster such as the BBC.
"This failing had the risk to undermine the exceptionally strong levels of trust that audiences would have placed in a documentary produced by the BBC about the conflict in Gaza."
The documentary was withdrawn from iPlayer in the month of February after the presenter's familial connections emerged, and in July an broadcaster's internal assessment concluded it violated the organization's journalistic standards on factual correctness.
A BBC spokesperson said: "The regulator's decision is in accordance with the findings of Peter Johnston's review, that there was a serious error in the film in relation to the corporation's content standards on truthfulness, which corresponds to clause 2.2 of Ofcom's Broadcasting Code.
"We have apologised for this and we agree with Ofcom's decision in complete. We will follow the penalty as soon as the schedule and language are determined."
