The BBC engaged in a "significant breach" of industry standards by omitting to mention that the presenter of a film about the Gaza situation was the son of a Hamas representative, according to regulatory body Ofcom.
An inquiry by the media regulator into Gaza: How to Survive a Warzone has concluded that the film was "substantially inaccurate".
The BBC's director general had earlier expressed regret, saying there had been "a major oversight in relation to factual correctness".
Ofcom has instructed the corporation to transmit a evening declaration about its conclusions.
"Given this constitutes a major infringement of our rules, we are ordering the corporation to air a message of our determinations against it on BBC2 at 21:00, with a schedule to be finalised," it said.
'Risk to Damage Credibility'
The authority's announcement said: "Our probe concluded that the programme's omission to reveal that the voice's father served in a post in the Hamas-controlled authority was materially misleading.
"This implied that the audience did not have essential details which may have been very significant to their evaluation of the voice and the details he presented.
"Trust is at the heart of the relationship between a television network and its viewers, notably for a national broadcasting corporation such as the public broadcaster.
"This oversight had the risk to erode the very considerable amounts of confidence that audiences would have placed in a documentary produced by the BBC about the Gaza conflict."
The film was withdrawn from the BBC's streaming service in the month of February after the presenter's familial connections were revealed, and in the month of July an internal BBC review found it breached the corporation's content policies on factual correctness.
A corporation official commented: "The regulator's decision is in agreement with the conclusions of the internal assessment, that there was a major oversight in the film in relation to the broadcaster's journalistic policies on accuracy, which aligns with clause 2.2 of the regulator's media standards.
"We have apologised for this and we accept the regulator's ruling in complete. We will adhere to the penalty as soon as the timing and language are finalised."
