The BBC committed a "significant breach" of media regulations by omitting to mention that the presenter of a programme about the Gaza situation was the offspring of a Hamas official, as determined by British broadcasting authority Ofcom.
An probe by the broadcasting watchdog into the documentary titled Gaza: How to Survive a Warzone has concluded that the film was "materially misleading".
The BBC's director general had already issued an apology, saying there had been "a serious error in relation to truthfulness".
Ofcom has directed the corporation to transmit a peak-time declaration about its conclusions.
"Since this amounts to a major infringement of our rules, we are instructing the corporation to broadcast a statement of our findings against it on the BBC's second channel at 21:00, with a timing to be finalised," the statement read.
'Possibility to Damage Confidence'
The regulator's announcement stated: "Our probe determined that the documentary's lack of disclosure that the voice's parent occupied a role in the Hamas-controlled authority was materially misleading.
"It meant that the public did not have vital facts which may have been highly relevant to their judgment of the voice and the information he provided.
"Confidence is at the core of the relationship between a media organization and its audience, particularly for a public service broadcaster such as the public broadcaster.
"This failing had the possibility to undermine the significantly high amounts of confidence that audiences would have put in a documentary produced by the BBC about the Israel-Gaza war."
The programme was withdrawn from the BBC's streaming service in last February after the presenter's family links emerged, and in this past July an corporation's own inquiry found it infringed the organization's journalistic standards on truthfulness.
A corporation official commented: "The regulator's decision is in agreement with the results of the corporation's inquiry, that there was a serious error in the programme in relation to the broadcaster's journalistic policies on truthfulness, which reflects clause 2.2 of the regulator's media standards.
"We have apologised for this and we agree with Ofcom's decision in full. We will comply with the sanction as soon as the schedule and language are confirmed."