The BBC was found to have committed a "major breach" of industry standards by omitting to mention that the narrator of a documentary about Gaza was the son of a Hamas official, according to regulatory body Ofcom.
An inquiry by the media regulator into Gaza: How to Survive a Warzone has concluded that the film was "significantly deceptive".
The BBC's director general had already issued an apology, saying there had been "a serious error in relation to accuracy".
The regulator has instructed the BBC to transmit a peak-time statement about its conclusions.
"As this represents a significant violation of our regulations, we are ordering the broadcaster to broadcast a message of our findings against it on the BBC's second channel at 9pm, with a timing to be finalised," the regulator stated.
'Risk to Damage Credibility'
The watchdog's announcement declared: "Our probe determined that the programme's failure to disclose that the voice's parent served in a position in the Hamas-administered administration was materially misleading.
"This implied that the audience did not have essential details which may have been highly relevant to their evaluation of the narrator and the content he shared.
"Credibility is at the center of the relationship between a media organization and its public, notably for a state-funded media outlet such as the public broadcaster.
"This failing had the possibility to erode the exceptionally strong degrees of confidence that audiences would have placed in a documentary produced by the BBC about the Israel-Gaza war."
The programme was removed from iPlayer in February after the boy's family links were revealed, and in the month of July an broadcaster's internal assessment found it breached the corporation's content policies on accuracy.
A BBC spokesperson said: "The Ofcom ruling is in accordance with the conclusions of Peter Johnston's review, that there was a major oversight in the programme in relation to the BBC's Editorial Guidelines on accuracy, which reflects regulation 2.2 of Ofcom's Broadcasting Code.
"We have apologised for this and we agree with the regulator's ruling in full. We will follow the sanction as soon as the date and language are determined."
