The BBC was found to have committed a "major breach" of industry standards by failing to disclose that the voice of a programme about the Gaza conflict was the offspring of a Hamas representative, according to British broadcasting authority Ofcom.
An inquiry by the broadcasting watchdog into the programme Gaza: How to Survive a Warzone has concluded that the documentary was "materially misleading".
The chief executive of the broadcaster had earlier expressed regret, stating there had been "a serious error in relation to truthfulness".
Ofcom has instructed the corporation to transmit a evening declaration about its decisions.
"Given this constitutes a major infringement of our rules, we are instructing the broadcaster to air a statement of our determinations against it on BBC Two at 9pm, with a schedule to be determined," it said.
'Possibility to Erode Trust'
The watchdog's report said: "Our investigation concluded that the documentary's lack of disclosure that the presenter's male guardian held a role in the Hamas-run administration was substantially inaccurate.
"Consequently that the viewers did not have essential details which may have been highly relevant to their assessment of the voice and the information he presented.
"Trust is at the heart of the relationship between a television network and its audience, especially for a state-funded media outlet such as the British Broadcasting Corporation.
"This error had the possibility to damage the very considerable levels of trust that viewers would have invested in a documentary produced by the BBC about the Israel-Gaza war."
The film was pulled from the BBC's streaming service in February after the presenter's familial connections came to light, and in the month of July an internal BBC review concluded it infringed the organization's editorial guidelines on factual correctness.
A corporation official stated: "The Ofcom ruling is in accordance with the conclusions of Peter Johnston's review, that there was a serious error in the documentary in relation to the BBC's Editorial Guidelines on truthfulness, which reflects clause 2.2 of the regulator's media standards.
"We issued an apology for this and we agree with the authority's determination in full. We will follow the penalty as soon as the schedule and language are finalised."
