The BBC engaged in a "serious breach" of broadcasting rules by not revealing that the voice of a documentary about the Gaza situation was the offspring of a Hamas official, according to regulatory body Ofcom.
An probe by Ofcom into the documentary titled Gaza: How to Survive a Warzone has determined that the programme was "substantially inaccurate".
The BBC's director general had earlier expressed regret, stating there had been "a major oversight in relation to accuracy".
Ofcom has ordered the corporation to air a prime-time statement about its conclusions.
"Given this constitutes a major infringement of our regulations, we are directing the broadcaster to broadcast a announcement of our findings against it on the BBC's second channel at 9pm, with a timing to be confirmed," the statement read.
'Risk to Erode Trust'
The regulator's statement declared: "Our probe found that the programme's lack of disclosure that the narrator's parent served in a position in the Hamas-run authority was substantially inaccurate.
"This implied that the audience did not have vital facts which may have been very significant to their assessment of the presenter and the information he shared.
"Credibility is at the core of the connection between a television network and its public, particularly for a public service broadcaster such as the BBC.
"This failing had the possibility to damage the significantly high levels of confidence that the public would have put in a BBC factual programme about the Israel-Gaza war."
The programme was removed from the online platform in February after the narrator's family links were revealed, and in this past July an internal BBC review concluded it infringed the corporation's journalistic standards on accuracy.
A BBC spokesperson said: "The regulator's decision is in agreement with the conclusions of the corporation's inquiry, that there was a major oversight in the documentary in relation to the corporation's content standards on truthfulness, which aligns with Rule 2.2 of the authority's broadcasting regulations.
"We expressed regret for this and we agree with the regulator's ruling in full. We will comply with the penalty as soon as the timing and wording are determined."