The BBC engaged in a "major breach" of broadcasting rules by not revealing that the narrator of a programme about the Gaza conflict was the offspring of a Hamas official, according to regulatory body Ofcom.
An inquiry by the broadcasting watchdog into Gaza: How to Survive a Warzone has concluded that the programme was "materially misleading".
The head of the BBC had already issued an apology, noting there had been "a serious error in relation to accuracy".
The authority has ordered the corporation to broadcast a evening declaration about its conclusions.
"Since this amounts to a major infringement of our rules, we are directing the BBC to transmit a announcement of our determinations against it on BBC2 at 21:00, with a schedule to be finalised," the statement read.
'Potential to Undermine Credibility'
The authority's report declared: "The inquiry we conducted concluded that the film's failure to disclose that the voice's father held a post in the Hamas-controlled administration was substantially inaccurate.
"It meant that the viewers did not have vital facts which may have been very significant to their judgment of the presenter and the details he shared.
"Credibility is at the core of the relationship between a television network and its audience, particularly for a state-funded media outlet such as the BBC.
"This oversight had the possibility to undermine the very considerable degrees of trust that audiences would have placed in a factual film from the broadcaster about the conflict in Gaza."
The film was withdrawn from the BBC's streaming service in February after the presenter's familial connections came to light, and in the month of July an broadcaster's internal assessment concluded it infringed the corporation's journalistic standards on truthfulness.
A corporation official stated: "The authority's determination is in accordance with the conclusions of Peter Johnston's review, that there was a serious error in the film in relation to the corporation's content standards on accuracy, which corresponds to regulation 2.2 of the regulator's media standards.
"We have apologised for this and we comply with Ofcom's decision in full. We will follow the sanction as soon as the timing and wording are finalised."
