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 child of a Hamas representative, as ruled by regulatory body Ofcom.
An inquiry by the broadcasting watchdog into the programme Gaza: How to Survive a Warzone has found that the programme was "substantially inaccurate".
The head of the BBC had already issued an apology, saying there had been "a significant failing in relation to accuracy".
Ofcom has ordered the broadcaster to air a evening statement about its decisions.
"As this represents a major infringement of our regulations, we are directing the BBC to air a message of our conclusions against it on BBC Two at nine o'clock in the evening, with a date to be determined," it said.
'Possibility to Erode Trust'
The watchdog's statement stated: "Our investigation found that the documentary's omission to reveal that the narrator's male guardian held a post in the Hamas-controlled authority was substantially inaccurate.
"Consequently that the audience did not have critical information which may have been extremely pertinent to their assessment of the narrator and the information he presented.
"Confidence is at the core of the connection between a television network and its public, notably for a national broadcasting corporation such as the British Broadcasting Corporation.
"This error had the risk to undermine the significantly high amounts of credibility that the public would have invested in a factual film from the broadcaster about the conflict in Gaza."
The film was removed from the BBC's streaming service in last February after the presenter's family links came to light, and in this past July an internal BBC review determined it infringed the broadcaster's journalistic standards on accuracy.
A BBC spokesperson commented: "The Ofcom ruling is in agreement with the conclusions 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 regulation 2.2 of the authority's broadcasting regulations.
"We expressed regret for this and we agree with Ofcom's decision in its entirety. We will adhere to the penalty as soon as the timing and wording are confirmed."
