The BBC engaged in a "serious breach" of broadcasting rules by not revealing that the presenter of a programme about the Gaza situation was the child of a Hamas representative, as ruled by regulatory body Ofcom.
An probe by Ofcom into Gaza: How to Survive a Warzone has concluded that the film was "substantially inaccurate".
The chief executive of the broadcaster had earlier expressed regret, noting there had been "a serious error in relation to accuracy".
Ofcom has directed the BBC to air a evening statement about its conclusions.
"Given this constitutes a serious breach of our rules, we are ordering the broadcaster to broadcast a announcement of our findings against it on BBC Two at 9pm, with a schedule to be confirmed," it said.
'Risk to Erode Confidence'
The regulator's report stated: "Our investigation found that the film's omission to reveal that the narrator's male guardian held a post in the Hamas-administered authority was materially misleading.
"Consequently that the viewers did not have essential details which may have been extremely pertinent to their assessment of the voice and the content he provided.
"Confidence is at the core of the bond between a broadcaster and its viewers, especially for a public service broadcaster such as the BBC.
"This error had the potential to erode the very considerable degrees of credibility that the public would have put in a factual film from the broadcaster about the Gaza conflict."
The programme was withdrawn from the BBC's streaming service in the month of February after the presenter's family links were revealed, and in the month of July an internal BBC review concluded it violated the corporation's content policies on accuracy.
A corporation official said: "The regulator's decision is in line with the conclusions of Peter Johnston's review, that there was a significant failing in the film in relation to the corporation's content standards on accuracy, which aligns with Rule 2.2 of the regulator's media standards.
"We have apologised for this and we agree with the regulator's ruling in its entirety. We will comply with the sanction as soon as the timing and wording are confirmed."
