The BBC committed a "serious breach" of media regulations by omitting to mention that the voice of a film about Gaza was the child of a Hamas representative, as ruled by British broadcasting authority Ofcom.
An probe by Ofcom into Gaza: How to Survive a Warzone has determined that the programme was "materially misleading".
The BBC's director general had earlier expressed regret, noting there had been "a major oversight in relation to accuracy".
Ofcom has ordered the corporation to air a evening announcement about its conclusions.
"Given this constitutes a serious breach of our regulations, we are ordering the broadcaster to broadcast a statement of our determinations against it on the BBC's second channel at 9pm, with a date to be finalised," the statement read.
'Risk to Undermine Confidence'
The regulator's report stated: "The inquiry we conducted found that the documentary's failure to disclose that the presenter's male guardian occupied a post in the Hamas-run government was substantially inaccurate.
"This implied that the public did not have essential details which may have been extremely pertinent to their assessment of the voice and the information he shared.
"Confidence is at the core of the relationship between a broadcaster and its viewers, notably for a national broadcasting corporation such as the British Broadcasting Corporation.
"This oversight had the risk to erode the very considerable amounts of trust that the public would have put in a factual film from the broadcaster about the Israel-Gaza war."
The film was removed from the BBC's streaming service in the month of February after the presenter's personal associations came to light, and in this past July an broadcaster's internal assessment found it infringed the corporation's journalistic standards on factual correctness.
A representative for the broadcaster said: "The regulator's decision is in agreement with the results of Peter Johnston's review, that there was a serious error in the film in relation to the BBC's Editorial Guidelines on factual correctness, which aligns with clause 2.2 of the authority's broadcasting regulations.
"We have apologised for this and we agree with Ofcom's decision in its entirety. We will comply with the sanction as soon as the timing and language are finalised."
