The BBC committed a "major breach" of media regulations by omitting to mention that the narrator of a programme about the Gaza situation was the child of a Hamas official, as determined by regulatory body Ofcom.
An probe by the broadcasting watchdog into the programme Gaza: How to Survive a Warzone has found that the documentary was "substantially inaccurate".
The BBC's director general had earlier expressed regret, stating there had been "a serious error in relation to factual correctness".
The regulator has instructed the corporation to transmit a prime-time announcement about its findings.
"Since this amounts to a major infringement of our rules, we are directing the broadcaster to air a message of our determinations against it on the BBC's second channel at nine o'clock in the evening, with a date to be finalised," it said.
'Risk to Undermine Credibility'
The authority's report declared: "The inquiry we conducted concluded that the documentary's lack of disclosure that the voice's father served in a position in the Hamas-run government was substantially inaccurate.
"It meant that the public did not have critical information which may have been extremely pertinent to their evaluation of the presenter and the information he presented.
"Credibility is at the center of the connection between a broadcaster and its audience, notably for a national broadcasting corporation such as the public broadcaster.
"This oversight had the potential to damage the significantly high degrees of confidence that the public would have invested in a BBC factual programme about the Israel-Gaza war."
The programme was withdrawn from the BBC's streaming service in February after the narrator's family links were revealed, and in this past July an broadcaster's internal assessment concluded it violated the organization's content policies on factual correctness.
A corporation official stated: "The Ofcom ruling is in line with the results of Peter Johnston's review, that there was a major oversight in the film in relation to the BBC's Editorial Guidelines on truthfulness, which corresponds to Rule 2.2 of Ofcom's Broadcasting Code.
"We issued an apology for this and we accept the regulator's ruling in complete. We will comply with the sanction as soon as the schedule and wording are determined."
