The public service broadcaster committed a "serious breach" of broadcasting rules by not revealing that the narrator of a film about the Gaza conflict was the child of a Hamas official, as determined by British broadcasting authority Ofcom.
An investigation by Ofcom into Gaza: How to Survive a Warzone has found that the documentary was "substantially inaccurate".
The chief executive of the broadcaster had already issued an apology, noting there had been "a significant failing in relation to truthfulness".
The regulator has instructed the broadcaster to air a evening announcement about its conclusions.
"As this represents a major infringement of our code, we are ordering the broadcaster to air a message of our determinations against it on BBC2 at 9pm, with a timing to be finalised," it said.
'Potential to Damage Trust'
The authority's statement said: "Our probe determined that the programme's failure to disclose that the narrator's father held a post in the Hamas-run administration was substantially inaccurate.
"Consequently that the viewers did not have vital facts which may have been extremely pertinent to their evaluation of the voice and the details he presented.
"Credibility is at the core of the bond between a television network and its public, notably for a state-funded media outlet such as the public broadcaster.
"This failing had the risk to erode the exceptionally strong degrees of credibility that audiences would have placed in a documentary produced by the BBC about the Gaza conflict."
The film was withdrawn from the BBC's streaming service in last February after the presenter's personal associations were revealed, and in the month of July an internal BBC review found it infringed the corporation's content policies on factual correctness.
A corporation official stated: "The regulator's decision is in line with the findings of Peter Johnston's review, that there was a serious error in the programme in relation to the BBC's Editorial Guidelines on accuracy, which reflects regulation 2.2 of the authority's broadcasting regulations.
"We have apologised for this and we comply with Ofcom's decision in full. We will adhere to the penalty as soon as the timing and wording are determined."
