The BBC engaged in a "major breach" of media regulations by omitting to mention that the voice of a documentary about the Gaza conflict was the child of a Hamas representative, according to regulatory body Ofcom.
An probe by the media regulator into the programme Gaza: How to Survive a Warzone has found that the film was "significantly deceptive".
The BBC's director general had already issued an apology, saying there had been "a significant failing in relation to truthfulness".
The authority has directed the BBC to broadcast a peak-time statement about its conclusions.
"As this represents a significant violation of our regulations, we are instructing the broadcaster to broadcast a announcement of our conclusions against it on BBC Two at 9pm, with a schedule to be confirmed," the regulator stated.
'Possibility to Damage Credibility'
The watchdog's statement declared: "The inquiry we conducted concluded that the film's omission to reveal that the voice's father occupied a post in the Hamas-administered administration was substantially inaccurate.
"It meant that the audience did not have essential details which may have been very significant to their evaluation of the voice and the information he presented.
"Credibility is at the core of the relationship between a broadcaster and its audience, especially for a public service broadcaster such as the BBC.
"This error had the possibility to erode the very considerable levels of confidence that audiences would have put in a factual film from the broadcaster about the conflict in Gaza."
The programme was withdrawn from the online platform in last February after the narrator's personal associations came to light, and in July an corporation's own inquiry determined it violated the broadcaster's journalistic standards on accuracy.
A representative for the broadcaster said: "The regulator's decision is in agreement with the findings of the corporation's inquiry, that there was a significant failing in the programme in relation to the BBC's Editorial Guidelines on accuracy, which reflects regulation 2.2 of the authority's broadcasting regulations.
"We expressed regret for this and we agree with the regulator's ruling in full. We will follow the penalty as soon as the schedule and wording are determined."
