The BBC committed a "significant breach" of broadcasting rules by omitting to mention that the narrator of a programme about the Gaza conflict was the offspring of a Hamas representative, as determined by British broadcasting authority Ofcom.
An probe by the broadcasting watchdog into the programme Gaza: How to Survive a Warzone has found that the film was "materially misleading".
The head of the BBC had earlier expressed regret, saying there had been "a major oversight in relation to factual correctness".
Ofcom has ordered the broadcaster to air a peak-time announcement about its decisions.
"Given this constitutes a major infringement of our code, we are ordering the broadcaster to air a announcement of our findings against it on BBC2 at nine o'clock in the evening, with a date to be determined," it said.
'Possibility to Erode Credibility'
The regulator's announcement said: "Our probe concluded that the film's omission to reveal that the presenter's male guardian held a role in the Hamas-run administration was significantly deceptive.
"It meant that the public did not have vital facts which may have been extremely pertinent to their evaluation of the narrator and the information he provided.
"Confidence is at the core of the connection between a broadcaster and its public, notably for a state-funded media outlet such as the British Broadcasting Corporation.
"This error had the risk to undermine the exceptionally strong levels of confidence that viewers would have placed in a documentary produced by the BBC about the Gaza conflict."
The film was withdrawn from the BBC's streaming service in the month of February after the presenter's family links came to light, and in the month of July an broadcaster's internal assessment determined it infringed the corporation's journalistic standards on accuracy.
A corporation official said: "The Ofcom ruling is in line with the results of the corporation's inquiry, that there was a significant failing in the documentary in relation to the corporation's content standards on factual correctness, which corresponds to clause 2.2 of Ofcom's Broadcasting Code.
"We issued an apology for this and we agree with the regulator's ruling in full. We will follow the penalty as soon as the date and wording are confirmed."
