The BBC committed a "significant breach" of broadcasting rules by failing to disclose that the voice of a programme about the Gaza conflict was the son of a Hamas representative, according to UK media regulator Ofcom.
An investigation by Ofcom into the programme Gaza: How to Survive a Warzone has concluded that the film was "significantly deceptive".
The head of the BBC had previously apologised, saying there had been "a serious error in relation to accuracy".
The regulator has ordered the BBC to air a prime-time declaration about its findings.
"Given this constitutes a significant violation of our code, we are directing the broadcaster to broadcast a statement of our findings against it on BBC Two at 21:00, with a schedule to be confirmed," the statement read.
'Possibility to Undermine Credibility'
The authority's report said: "Our investigation determined that the film's failure to disclose that the narrator's father held a post in the Hamas-run government was significantly deceptive.
"It meant that the viewers did not have vital facts which may have been highly relevant to their judgment of the presenter and the content he provided.
"Trust is at the center of the connection between a media organization and its public, especially for a public service broadcaster such as the BBC.
"This error had the risk to erode the exceptionally strong levels of confidence that viewers would have placed in a BBC factual programme about the Gaza conflict."
The film was pulled from the BBC's streaming service in the month of February after the narrator's family links emerged, and in July an corporation's own inquiry found it infringed the corporation's editorial guidelines on truthfulness.
A representative for the broadcaster stated: "The regulator's decision is in agreement with the findings of the corporation's inquiry, that there was a significant failing in the film in relation to the corporation's content standards on accuracy, which reflects regulation 2.2 of the authority's broadcasting regulations.
"We have apologised for this and we accept Ofcom's decision in complete. We will comply with the penalty as soon as the date and language are confirmed."
