The British broadcaster was found to have committed a "major breach" of media regulations by omitting to mention that the voice of a programme about Gaza was the son of a Hamas official, according to British broadcasting authority Ofcom.
An inquiry by the broadcasting watchdog into the programme Gaza: How to Survive a Warzone has determined that the programme was "substantially inaccurate".
The BBC's director general had previously apologised, noting there had been "a serious error in relation to accuracy".
Ofcom has ordered the corporation to transmit a evening announcement about its conclusions.
"Since this amounts to a significant violation of our regulations, we are instructing the BBC to transmit a statement of our findings against it on BBC Two at 21:00, with a date to be determined," the statement read.
'Risk to Erode Credibility'
The authority's report said: "Our investigation determined that the documentary's omission to reveal that the narrator's parent served in a position in the Hamas-administered authority was materially misleading.
"This implied that the public did not have essential details which may have been highly relevant to their evaluation of the presenter and the information he provided.
"Trust is at the core of the relationship between a television network and its public, notably for a national broadcasting corporation such as the British Broadcasting Corporation.
"This oversight had the possibility to damage the very considerable amounts of credibility that audiences would have placed in a documentary produced by the BBC about the Gaza conflict."
The programme was withdrawn from iPlayer in last February after the narrator's family links were revealed, and in July an corporation's own inquiry found it breached the corporation's content policies on truthfulness.
A BBC spokesperson said: "The regulator's decision is in line with the results of the corporation's inquiry, that there was a serious error in the film in relation to the BBC's Editorial Guidelines on accuracy, which corresponds to clause 2.2 of the authority's broadcasting regulations.
"We have apologised 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 finalised."
