The BBC was found to have committed a "serious breach" of broadcasting rules by omitting to mention that the presenter of a film about Gaza was the offspring of a Hamas official, as ruled by regulatory body Ofcom.
An probe by Ofcom into Gaza: How to Survive a Warzone has found that the documentary was "substantially inaccurate".
The BBC's director general had earlier expressed regret, stating there had been "a serious error in relation to accuracy".
Ofcom has instructed the BBC to broadcast a peak-time declaration about its findings.
"Given this constitutes a major infringement of our code, we are directing the BBC to transmit a statement of our conclusions against it on BBC2 at 21:00, with a date to be confirmed," the regulator stated.
'Possibility to Erode Credibility'
The regulator's announcement stated: "The inquiry we conducted found that the programme's failure to disclose that the presenter's parent held a position in the Hamas-administered authority was substantially inaccurate.
"Consequently that the viewers did not have vital facts which may have been highly relevant to their evaluation of the narrator and the content he shared.
"Credibility is at the core of the bond between a television network and its public, particularly for a national broadcasting corporation such as the public broadcaster.
"This failing had the potential to erode the very considerable degrees of credibility that the public would have put in a documentary produced by the BBC about the Gaza conflict."
The film was withdrawn from the online platform in February after the presenter's personal associations came to light, and in July an broadcaster's internal assessment concluded it violated the organization's editorial guidelines on truthfulness.
A representative for the broadcaster said: "The Ofcom ruling is in accordance with the findings of the corporation's inquiry, that there was a major oversight in the programme in relation to the broadcaster's journalistic policies on truthfulness, which aligns with regulation 2.2 of the regulator's media standards.
"We have apologised for this and we comply with the regulator's ruling in full. We will follow the sanction as soon as the date and language are finalised."