The BBC was found to have committed a "significant breach" of broadcasting rules by omitting to mention that the narrator of a film about the Gaza conflict was the child of a Hamas representative, as ruled by British broadcasting authority Ofcom.
An investigation by the media regulator into the documentary titled Gaza: How to Survive a Warzone has concluded that the film was "substantially inaccurate".
The BBC's director general had previously apologised, noting there had been "a serious error in relation to factual correctness".
The authority has directed the corporation to broadcast a prime-time announcement about its conclusions.
"Since this amounts to a serious breach of our code, we are ordering the BBC to air a announcement of our conclusions against it on the BBC's second channel at 21:00, with a timing to be determined," it said.
'Risk to Undermine Trust'
The watchdog's statement declared: "Our probe found that the documentary's lack of disclosure that the voice's father occupied a post in the Hamas-controlled authority was significantly deceptive.
"Consequently that the viewers did not have critical information which may have been highly relevant to their judgment of the narrator and the content he shared.
"Credibility is at the core of the bond between a media organization and its viewers, especially for a public service broadcaster such as the British Broadcasting Corporation.
"This oversight had the possibility to erode the very considerable degrees of credibility that the public would have put in a factual film from the broadcaster about the Gaza conflict."
The programme was withdrawn from the online platform in February after the presenter's familial connections were revealed, and in July an corporation's own inquiry concluded it infringed the organization's editorial guidelines on accuracy.
A corporation official said: "The authority's determination is in line with the findings of Peter Johnston's review, that there was a major oversight in the documentary in relation to the BBC's Editorial Guidelines on factual correctness, which corresponds to clause 2.2 of Ofcom's Broadcasting Code.
"We have apologised for this and we comply with the regulator's ruling in its entirety. We will comply with the directive as soon as the date and language are confirmed."
