The British broadcaster committed a "significant breach" of broadcasting rules by failing to disclose that the presenter of a film about Gaza was the son of a Hamas administrator, as ruled by British broadcasting authority Ofcom.
An investigation by Ofcom into the programme Gaza: How to Survive a Warzone has found that the film was "significantly deceptive".
The head of the BBC had already issued an apology, noting there had been "a significant failing in relation to factual correctness".
The authority has ordered the broadcaster to air a peak-time announcement about its conclusions.
"As this represents a major infringement of our code, we are directing the corporation to broadcast a announcement of our determinations against it on BBC Two at 21:00, with a timing to be determined," it said.
'Potential to Undermine Confidence'
The watchdog's report declared: "Our investigation found that the programme's omission to reveal that the presenter's parent held a role in the Hamas-controlled government was substantially inaccurate.
"Consequently that the viewers did not have essential details which may have been highly relevant to their judgment of the narrator and the details he provided.
"Trust is at the center of the connection between a media organization and its audience, especially for a national broadcasting corporation such as the public broadcaster.
"This error had the risk to erode the exceptionally strong degrees of confidence that audiences would have placed in a documentary produced by the BBC about the Gaza conflict."
The programme was removed from the BBC's streaming service in the month of February after the presenter's personal associations emerged, and in this past July an corporation's own inquiry concluded it breached the broadcaster's content policies on accuracy.
A BBC spokesperson commented: "The authority's determination is in accordance with the results 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 aligns with regulation 2.2 of the authority's broadcasting regulations.
"We issued an apology for this and we agree with the regulator's ruling in complete. We will adhere to the penalty as soon as the timing and wording are determined."