The BBC was found to have committed a "serious breach" of industry standards by omitting to mention that the narrator of a film about the Gaza conflict was the son of a Hamas administrator, according to UK media regulator Ofcom.
An probe by the broadcasting watchdog into Gaza: How to Survive a Warzone has determined that the documentary was "materially misleading".
The chief executive of the broadcaster had earlier expressed regret, stating there had been "a serious error in relation to truthfulness".
Ofcom has ordered the broadcaster to air a evening declaration about its conclusions.
"As this represents a serious breach of our code, we are instructing the BBC to broadcast a message of our findings against it on the BBC's second channel at nine o'clock in the evening, with a date to be finalised," it said.
'Risk to Damage Credibility'
The watchdog's report stated: "The inquiry we conducted determined that the film's lack of disclosure that the presenter's male guardian occupied a post in the Hamas-administered administration was materially misleading.
"This implied that the audience did not have vital facts which may have been highly relevant to their judgment of the voice and the details he presented.
"Credibility is at the heart of the connection between a broadcaster and its viewers, notably for a public service broadcaster such as the BBC.
"This failing had the potential to damage the very considerable levels of confidence that audiences would have invested in a factual film from the broadcaster about the Israel-Gaza war."
The programme was withdrawn from iPlayer in last February after the presenter's family links were revealed, and in this past July an internal BBC review found it violated the corporation's editorial guidelines on truthfulness.
A corporation official commented: "The Ofcom ruling is in agreement with the conclusions of the internal assessment, that there was a significant failing in the documentary in relation to the corporation's content standards on truthfulness, which aligns with regulation 2.2 of the authority's broadcasting regulations.
"We issued an apology for this and we accept the authority's determination in its entirety. We will follow the directive as soon as the schedule and language are confirmed."
