The BBC committed a "significant breach" of broadcasting rules by not revealing that the voice of a programme about the Gaza conflict was the child of a Hamas official, as ruled by British broadcasting authority Ofcom.
An inquiry by the broadcasting watchdog into the programme Gaza: How to Survive a Warzone has found that the documentary was "substantially inaccurate".
The chief executive of the broadcaster had earlier expressed regret, noting there had been "a significant failing in relation to factual correctness".
Ofcom has instructed the corporation to transmit a evening statement about its conclusions.
"As this represents a serious breach of our regulations, we are directing the corporation to transmit a announcement of our conclusions against it on the BBC's second channel at 21:00, with a timing to be finalised," it said.
'Possibility to Undermine Confidence'
The regulator's announcement declared: "The inquiry we conducted concluded that the film's failure to disclose that the narrator's father occupied a position in the Hamas-controlled administration was significantly deceptive.
"This implied that the audience did not have essential details which may have been very significant to their evaluation of the narrator and the content he provided.
"Confidence is at the core of the bond between a media organization and its viewers, notably for a state-funded media outlet such as the BBC.
"This error had the potential to damage the very considerable levels of trust that the public would have placed in a factual film from the broadcaster about the conflict in Gaza."
The documentary was pulled from iPlayer in the month of February after the presenter's familial connections were revealed, and in July an corporation's own inquiry determined it infringed the broadcaster's editorial guidelines on factual correctness.
A BBC spokesperson stated: "The Ofcom ruling is in line with the results of Peter Johnston's review, that there was a serious error in the documentary in relation to the BBC's Editorial Guidelines on factual correctness, which aligns with clause 2.2 of Ofcom's Broadcasting Code.
"We have apologised for this and we comply with the regulator's ruling in complete. We will follow the penalty as soon as the timing and wording are determined."
