The British broadcaster was found to have committed a "major breach" of industry standards by omitting to mention that the narrator of a film about the Gaza situation was the son of a Hamas administrator, as ruled by regulatory body Ofcom.
An inquiry by Ofcom into the programme Gaza: How to Survive a Warzone has determined that the film was "substantially inaccurate".
The chief executive of the broadcaster had already issued an apology, stating there had been "a significant failing in relation to truthfulness".
The regulator has ordered the broadcaster to broadcast a prime-time announcement about its findings.
"Since this amounts to a serious breach of our rules, we are instructing the BBC to air a announcement of our findings against it on the BBC's second channel at 9pm, with a date to be finalised," the statement read.
'Risk to Undermine Trust'
The regulator's statement declared: "The inquiry we conducted determined that the documentary's failure to disclose that the narrator's parent served in a post in the Hamas-controlled administration was significantly deceptive.
"It meant that the viewers did not have critical information which may have been very significant to their evaluation of the presenter and the content he provided.
"Trust is at the heart of the relationship between a broadcaster and its viewers, notably for a state-funded media outlet such as the British Broadcasting Corporation.
"This error had the risk to undermine the exceptionally strong amounts of confidence that audiences would have invested in a factual film from the broadcaster about the Gaza conflict."
The film was pulled from iPlayer in February after the presenter's family links emerged, and in the month of July an corporation's own inquiry concluded it violated the organization's content policies on factual correctness.
A BBC spokesperson said: "The authority's determination is in accordance with the results of Peter Johnston's review, that there was a significant failing in the programme in relation to the BBC's Editorial Guidelines on factual correctness, which reflects regulation 2.2 of Ofcom's Broadcasting Code.
"We issued an apology for this and we comply with Ofcom's decision in complete. We will follow the sanction as soon as the timing and wording are confirmed."
