The British broadcaster was found to have committed a "major breach" of industry standards by not revealing that the presenter of a film about Gaza was the offspring of a Hamas official, as determined by British broadcasting authority Ofcom.
An inquiry by Ofcom into the programme Gaza: How to Survive a Warzone has determined that the documentary was "materially misleading".
The head of the BBC had earlier expressed regret, noting there had been "a major oversight in relation to accuracy".
The regulator has ordered the BBC to air a evening announcement about its conclusions.
"Given this constitutes a serious breach of our code, we are directing the BBC to transmit a message of our findings against it on BBC Two at nine o'clock in the evening, with a date to be determined," it said.
'Risk to Damage Trust'
The watchdog's statement stated: "The inquiry we conducted determined that the programme's failure to disclose that the narrator's male guardian served in a position in the Hamas-controlled authority was substantially inaccurate.
"This implied that the public did not have critical information which may have been very significant to their assessment of the narrator and the content he provided.
"Confidence is at the heart of the bond between a media organization and its public, notably for a national broadcasting corporation such as the BBC.
"This error had the possibility to damage the significantly high levels of credibility that audiences would have placed in a factual film from the broadcaster about the conflict in Gaza."
The programme was removed from the BBC's streaming service in the month of February after the narrator's personal associations were revealed, and in this past July an internal BBC review found it infringed the corporation's editorial guidelines on accuracy.
A corporation official said: "The Ofcom ruling is in line with the findings of the internal assessment, that there was a serious error in the programme in relation to the corporation's content standards on truthfulness, which reflects clause 2.2 of the regulator's media standards.
"We expressed regret for this and we comply with the authority's determination in full. We will adhere to the penalty as soon as the schedule and wording are determined."
