The BBC committed a "serious breach" of media regulations by not revealing that the voice of a programme about Gaza was the son of a Hamas administrator, according to British broadcasting authority Ofcom.
An inquiry by Ofcom into the documentary titled Gaza: How to Survive a Warzone has concluded that the documentary was "significantly deceptive".
The BBC's director general had already issued an apology, noting there had been "a serious error in relation to truthfulness".
The authority has ordered the corporation to broadcast a evening declaration about its findings.
"As this represents a major infringement of our rules, we are directing the broadcaster to broadcast a announcement of our conclusions against it on BBC2 at nine o'clock in the evening, with a date to be determined," it said.
'Possibility to Damage Trust'
The watchdog's report said: "Our probe determined that the programme's lack of disclosure that the presenter's parent occupied a post in the Hamas-controlled government was materially misleading.
"Consequently that the audience did not have vital facts which may have been very significant to their evaluation of the voice and the content he provided.
"Credibility is at the core of the bond between a broadcaster and its audience, notably for a state-funded media outlet such as the British Broadcasting Corporation.
"This error had the potential to erode the very considerable amounts of trust that the public would have invested in a documentary produced by the BBC about the conflict in Gaza."
The programme was withdrawn from iPlayer in February after the presenter's family links came to light, and in the month of July an corporation's own inquiry concluded it violated the organization's editorial guidelines on truthfulness.
A BBC spokesperson stated: "The Ofcom ruling is in agreement with the conclusions of the internal assessment, that there was a serious error in the programme in relation to the corporation's content standards on factual correctness, which reflects regulation 2.2 of Ofcom's Broadcasting Code.
"We issued an apology for this and we comply with Ofcom's decision in full. We will follow the sanction as soon as the schedule and wording are determined."
