The British broadcaster committed a "serious breach" of industry standards by omitting to mention that the narrator of a documentary about the Gaza conflict was the son of a Hamas administrator, according to British broadcasting authority 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, saying there had been "a significant failing in relation to accuracy".
Ofcom has instructed the corporation to air a evening announcement about its findings.
"Given this constitutes a major infringement of our rules, we are directing the corporation to transmit a message of our determinations against it on BBC2 at nine o'clock in the evening, with a schedule to be determined," the regulator stated.
The regulator's report declared: "Our investigation concluded that the documentary's omission to reveal that the voice's parent occupied a post in the Hamas-run government was materially misleading.
"Consequently that the viewers did not have critical information which may have been very significant to their assessment of the narrator and the information he shared.
"Confidence is at the heart of the bond between a television network and its viewers, notably for a national broadcasting corporation such as the British Broadcasting Corporation.
"This failing had the potential to erode the exceptionally strong amounts of confidence that audiences would have put in a documentary produced by the BBC about the Gaza conflict."
The documentary was withdrawn from the online platform in the month of February after the presenter's familial connections emerged, and in July an internal BBC review determined it breached the corporation's editorial guidelines on truthfulness.
A representative for the broadcaster stated: "The regulator's decision is in accordance with the results of Peter Johnston's review, that there was a major oversight in the documentary in relation to the corporation's content standards on accuracy, which aligns with clause 2.2 of the regulator's media standards.
"We issued an apology for this and we accept Ofcom's decision in complete. We will comply with the penalty as soon as the timing and wording are determined."