The BBC was found to have committed a "serious breach" of broadcasting rules by not revealing that the presenter of a programme about the Gaza situation was the offspring of a Hamas representative, as determined by regulatory body Ofcom.
An probe by the media regulator into the programme Gaza: How to Survive a Warzone has concluded that the film was "significantly deceptive".
The chief executive of the broadcaster had previously apologised, saying there had been "a major oversight in relation to truthfulness".
The regulator has ordered the broadcaster to transmit a evening announcement about its findings.
"Since this amounts to a major infringement of our rules, we are instructing the BBC to transmit a announcement of our conclusions against it on BBC2 at nine o'clock in the evening, with a schedule to be finalised," the statement read.
'Potential to Damage Trust'
The authority's statement said: "Our investigation determined that the programme's lack of disclosure that the voice's parent held a post in the Hamas-administered authority was significantly deceptive.
"It meant that the audience did not have critical information which may have been highly relevant to their evaluation of the narrator and the details he presented.
"Credibility is at the center of the relationship between a television network and its audience, especially for a state-funded media outlet such as the public broadcaster.
"This failing had the risk to damage the very considerable degrees of credibility that audiences would have put in a documentary produced by the BBC about the Israel-Gaza war."
The documentary was withdrawn from the BBC's streaming service in February after the presenter's personal associations came to light, and in this past July an broadcaster's internal assessment concluded it breached the corporation's content policies on truthfulness.
A corporation official said: "The Ofcom ruling is in agreement with the findings of Peter Johnston's review, that there was a major oversight in the film in relation to the broadcaster's journalistic policies on factual correctness, which reflects Rule 2.2 of Ofcom's Broadcasting Code.
"We have apologised for this and we accept Ofcom's decision in full. We will comply with the penalty as soon as the timing and wording are determined."
