The BBC committed a "major breach" of broadcasting rules by omitting to mention that the presenter of a documentary about the Gaza conflict was the son of a Hamas representative, according to UK media regulator Ofcom.
An probe by Ofcom into the programme Gaza: How to Survive a Warzone has found that the programme was "significantly deceptive".
The chief executive of the broadcaster had already issued an apology, saying there had been "a major oversight in relation to accuracy".
The authority has ordered the corporation to air a evening declaration about its conclusions.
"Given this constitutes a serious breach of our rules, we are directing the corporation to air a message of our conclusions against it on the BBC's second channel at nine o'clock in the evening, with a timing to be confirmed," it said.
'Possibility to Erode Credibility'
The authority's announcement declared: "Our investigation concluded that the programme's omission to reveal that the presenter's male guardian held a post in the Hamas-controlled authority was materially misleading.
"It meant that the viewers did not have vital facts which may have been extremely pertinent to their evaluation of the voice and the content he shared.
"Trust is at the center of the bond between a television network and its viewers, especially for a national broadcasting corporation such as the British Broadcasting Corporation.
"This oversight had the possibility to undermine the very considerable levels of credibility that audiences would have invested in a BBC factual programme about the Israel-Gaza war."
The film was removed from the BBC's streaming service in last February after the presenter's family links emerged, and in July an broadcaster's internal assessment found it infringed the broadcaster's content policies on truthfulness.
A corporation official commented: "The Ofcom ruling is in agreement with the conclusions of Peter Johnston's review, that there was a serious error in the film in relation to the broadcaster's journalistic policies on factual correctness, which reflects clause 2.2 of Ofcom's Broadcasting Code.
"We issued an apology for this and we accept the regulator's ruling in its entirety. We will follow the sanction as soon as the date and language are confirmed."
