The BBC was found to have committed a "serious breach" of broadcasting rules by not revealing that the voice of a programme about the Gaza conflict was the son of a Hamas official, as ruled by UK media regulator Ofcom.
An investigation by the media regulator into the documentary titled Gaza: How to Survive a Warzone has determined that the programme was "substantially inaccurate".
The chief executive of the broadcaster had earlier expressed regret, stating there had been "a major oversight in relation to accuracy".
Ofcom has directed the broadcaster to air a peak-time declaration about its findings.
"Given this constitutes a significant violation of our rules, we are ordering the corporation to air a message of our findings against it on BBC Two at 9pm, with a timing to be finalised," the statement read.
'Risk to Erode Trust'
The watchdog's report declared: "Our probe concluded that the programme's lack of disclosure that the voice's parent held a role in the Hamas-controlled government was substantially inaccurate.
"This implied that the viewers did not have essential details which may have been highly relevant to their evaluation of the presenter and the information he presented.
"Credibility is at the heart of the connection between a television network and its audience, especially for a national broadcasting corporation such as the public broadcaster.
"This error had the risk to undermine the exceptionally strong levels of credibility that the public would have placed in a factual film from the broadcaster about the Gaza conflict."
The documentary was removed from the BBC's streaming service in last February after the narrator's family links were revealed, and in this past July an corporation's own inquiry concluded it infringed the corporation's journalistic standards on truthfulness.
A representative for the broadcaster stated: "The Ofcom ruling is in line with the conclusions of the internal assessment, that there was a significant failing in the programme in relation to the BBC's Editorial Guidelines on factual correctness, which corresponds to Rule 2.2 of the authority's broadcasting regulations.
"We have apologised for this and we agree with Ofcom's decision in its entirety. We will comply with the penalty as soon as the schedule and language are determined."
