The BBC committed a "major breach" of broadcasting rules by omitting to mention that the presenter of a documentary about the Gaza situation was the offspring of a Hamas representative, as determined by British broadcasting authority Ofcom.
An investigation by Ofcom into the programme Gaza: How to Survive a Warzone has concluded that the programme was "materially misleading".
The chief executive of the broadcaster had already issued an apology, stating there had been "a serious error in relation to truthfulness".
Ofcom has directed the corporation to transmit a evening announcement about its findings.
"Given this constitutes a major infringement of our regulations, we are instructing the broadcaster to air a message of our determinations against it on BBC Two at 21:00, with a date to be confirmed," it said.
'Risk to Erode Credibility'
The watchdog's statement said: "The inquiry we conducted found that the documentary's omission to reveal that the presenter's parent held a role in the Hamas-run authority was substantially inaccurate.
"It meant that the viewers did not have essential details which may have been very significant to their assessment of the narrator and the content he presented.
"Trust is at the heart of the relationship between a media organization and its viewers, especially for a public service broadcaster such as the British Broadcasting Corporation.
"This oversight had the potential to damage the very considerable degrees of trust that audiences would have invested in a factual film from the broadcaster about the Gaza conflict."
The film was withdrawn from the online platform in February after the narrator's family links emerged, and in July an internal BBC review found it infringed the broadcaster's editorial guidelines on factual correctness.
A BBC spokesperson said: "The authority's determination is in agreement with the conclusions of the internal assessment, that there was a significant failing in the programme in relation to the BBC's Editorial Guidelines on truthfulness, which corresponds to Rule 2.2 of the regulator's media standards.
"We issued an apology for this and we agree with the authority's determination in full. We will adhere to the penalty as soon as the schedule and wording are confirmed."
