The BBC was found to have committed a "significant breach" of industry standards by omitting to mention that the presenter of a programme about the Gaza situation was the offspring of a Hamas official, as determined by UK media regulator Ofcom.
An probe by the media regulator into Gaza: How to Survive a Warzone has found that the film was "materially misleading".
The BBC's director general had earlier expressed regret, noting there had been "a major oversight in relation to truthfulness".
Ofcom has directed the BBC to air a evening declaration about its findings.
"Given this constitutes a significant violation of our rules, we are instructing the BBC to air a statement of our conclusions against it on the BBC's second channel at 21:00, with a schedule to be confirmed," the statement read.
'Potential to Damage Trust'
The regulator's statement declared: "The inquiry we conducted determined that the documentary's lack of disclosure that the presenter's parent served in a role in the Hamas-controlled authority was materially misleading.
"Consequently that the viewers did not have essential details which may have been extremely pertinent to their assessment of the narrator and the information he provided.
"Confidence is at the center of the connection between a television network and its audience, particularly for a state-funded media outlet such as the British Broadcasting Corporation.
"This failing had the potential to damage the exceptionally strong amounts of confidence that viewers would have placed in a factual film from the broadcaster about the Gaza conflict."
The programme was withdrawn from the BBC's streaming service in last February after the narrator's personal associations came to light, and in July an corporation's own inquiry found it infringed the organization's journalistic standards on factual correctness.
A BBC spokesperson said: "The regulator's decision is in accordance with the results of Peter Johnston's review, that there was a serious error in the documentary in relation to the BBC's Editorial Guidelines on factual correctness, which corresponds to Rule 2.2 of the regulator's media standards.
"We have apologised for this and we accept the regulator's ruling in its entirety. We will adhere to the sanction as soon as the date and wording are confirmed."
