The BBC engaged in a "significant breach" of media regulations by failing to disclose that the voice of a documentary about the Gaza conflict was the son of a Hamas representative, as determined by British broadcasting authority Ofcom.
An investigation by the media regulator into Gaza: How to Survive a Warzone has found that the programme was "substantially inaccurate".
The BBC's director general had already issued an apology, noting there had been "a serious error in relation to truthfulness".
The regulator has instructed the broadcaster to air a prime-time statement about its findings.
"Since this amounts to a significant violation of our rules, we are directing the BBC to transmit a message of our findings against it on BBC Two at 21:00, with a timing to be finalised," it said.
'Possibility to Damage Credibility'
The watchdog's statement declared: "Our probe concluded that the documentary's failure to disclose that the presenter's male guardian held a role in the Hamas-controlled government was significantly deceptive.
"It meant that the audience did not have vital facts which may have been very significant to their judgment of the narrator and the content he shared.
"Credibility is at the heart of the relationship between a media organization and its viewers, especially for a public service broadcaster such as the BBC.
"This error had the potential to erode the exceptionally strong amounts of confidence that the public would have invested in a BBC factual programme about the Israel-Gaza war."
The documentary was withdrawn from iPlayer in the month of February after the presenter's family links emerged, and in July an corporation's own inquiry found it violated the corporation's editorial guidelines on truthfulness.
A BBC spokesperson said: "The authority's determination is in agreement with the findings of the internal assessment, that there was a major oversight in the film in relation to the corporation's content standards on accuracy, which corresponds to Rule 2.2 of Ofcom's Broadcasting Code.
"We have apologised for this and we accept the authority's determination in complete. We will comply with the directive as soon as the date and language are determined."
