The BBC committed a "major breach" of industry standards by failing to disclose that the voice of a film about Gaza was the offspring of a Hamas official, as ruled by British broadcasting authority Ofcom.
An probe by Ofcom into the documentary titled Gaza: How to Survive a Warzone has determined that the film was "significantly deceptive".
The head of the BBC had already issued an apology, stating there had been "a significant failing in relation to factual correctness".
Ofcom has directed the corporation to air a evening declaration about its findings.
"Since this amounts to a significant violation of our regulations, we are instructing the BBC to transmit a announcement of our findings against it on the BBC's second channel at 21:00, with a schedule to be confirmed," the regulator stated.
'Risk to Erode Trust'
The authority's report said: "Our investigation determined that the film's failure to disclose that the voice's father held a post in the Hamas-controlled administration was substantially inaccurate.
"Consequently that the viewers did not have critical information which may have been extremely pertinent to their assessment of the narrator and the information he provided.
"Confidence is at the heart of the connection between a television network and its public, notably for a public service broadcaster such as the British Broadcasting Corporation.
"This error had the potential to erode the exceptionally strong amounts of confidence that the public would have placed in a documentary produced by the BBC about the Gaza conflict."
The documentary was removed from the BBC's streaming service in February after the presenter's personal associations came to light, and in July an broadcaster's internal assessment determined it violated the organization's editorial guidelines on accuracy.
A BBC spokesperson said: "The authority's determination is in accordance with the findings of Peter Johnston's review, that there was a major oversight in the programme in relation to the corporation's content standards on accuracy, which corresponds to clause 2.2 of Ofcom's Broadcasting Code.
"We issued an apology for this and we comply with the regulator's ruling in complete. We will adhere to the sanction as soon as the schedule and language are finalised."
