The BBC committed a "serious breach" of industry standards by omitting to mention that the voice of a programme about the Gaza conflict was the offspring of a Hamas representative, according to regulatory body Ofcom.
An investigation by the media regulator into the programme Gaza: How to Survive a Warzone has concluded that the documentary was "materially misleading".
The BBC's director general had already issued an apology, stating there had been "a serious error in relation to truthfulness".
The regulator has instructed the broadcaster to air a prime-time announcement about its decisions.
"As this represents a serious breach of our code, we are ordering the broadcaster to air a statement of our determinations against it on BBC Two at 9pm, with a date to be confirmed," it said.
'Risk to Erode Trust'
The regulator's report stated: "The inquiry we conducted determined that the documentary's failure to disclose that the presenter's father held a position in the Hamas-administered authority was significantly deceptive.
"Consequently that the public did not have critical information which may have been very significant to their judgment of the narrator and the content he provided.
"Confidence is at the center of the bond between a broadcaster and its public, particularly for a public service broadcaster such as the public broadcaster.
"This oversight had the potential to damage the exceptionally strong amounts of trust that viewers would have placed in a documentary produced by the BBC about the conflict in Gaza."
The documentary was pulled from iPlayer in the month of February after the presenter's familial connections emerged, and in July an broadcaster's internal assessment found it violated the corporation's content policies on truthfulness.
A corporation official said: "The Ofcom ruling is in line with the findings of the internal assessment, that there was a significant failing in the programme in relation to the broadcaster's journalistic policies on accuracy, which corresponds to clause 2.2 of the authority's broadcasting regulations.
"We expressed regret for this and we comply with Ofcom's decision in its entirety. We will adhere to the penalty as soon as the timing and language are determined."
