The BBC committed a "significant breach" of media regulations by not revealing that the presenter of a programme about Gaza was the son of a Hamas official, as ruled by British broadcasting authority Ofcom.
An probe by the media regulator into the programme Gaza: How to Survive a Warzone has found that the programme was "significantly deceptive".
The BBC's director general had already issued an apology, saying there had been "a major oversight in relation to accuracy".
Ofcom has ordered the corporation to transmit a prime-time declaration about its findings.
"As this represents a significant violation of our rules, we are ordering the BBC to broadcast a message of our conclusions against it on BBC2 at nine o'clock in the evening, with a timing to be confirmed," it said.
'Possibility to Erode Trust'
The watchdog's announcement stated: "The inquiry we conducted concluded that the documentary's omission to reveal that the voice's parent served in a post in the Hamas-administered government was materially misleading.
"It meant that the viewers did not have critical information which may have been highly relevant to their evaluation of the narrator and the content he presented.
"Trust is at the core of the relationship between a television network and its viewers, especially for a public service broadcaster such as the BBC.
"This oversight had the risk to erode the very considerable degrees of credibility that the public would have put in a BBC factual programme about the Gaza conflict."
The programme was withdrawn from the online platform in February after the boy's personal associations came to light, and in this past July an corporation's own inquiry concluded it breached the broadcaster's journalistic standards on truthfulness.
A BBC spokesperson stated: "The regulator's decision is in accordance with the conclusions of Peter Johnston's review, that there was a significant failing in the film in relation to the corporation's content standards on factual correctness, which corresponds to regulation 2.2 of the regulator's media standards.
"We issued an apology for this and we accept Ofcom's decision in full. We will follow the directive as soon as the date and wording are confirmed."
